Top 50+ COBOL Interview Questions and Answers

COBOL Interview Questions and Answers

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Ashwath (COBOL Developer )

Ashwath is a skilled COBOL Developer dedicated to maintaining and enhancing robust legacy systems. Proficient in COBOL programming, he transforms business requirements into efficient code while ensuring system reliability and performance. Ashwath stays informed about the latest trends and best practices in mainframe development.

Last updated on 14th Oct 2024| 3843

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A COBOL Developer specializes in developing robust and efficient business applications. They utilize COBOL programming language along with technologies like JCL and DB2 to create and maintain applications that support critical operations. With a focus on performance and reliability, they ensure that applications handle large volumes of data efficiently and integrate smoothly with legacy systems. Their work connects business requirements with technical implementation, contributing significantly to operational success.

1. What is COBOL? What are its characteristics?

Ans:

COBOL (Common Business-Oriented Language) is one of the identified high-level programming languages, and it is used for business-oriented applications. Its syntax is modeled from the English language, which renders one needing to learn how to program an easier understanding. It is also effective in processing large volumes of data, especially those transactional types. Little modification is required on different hardware and operating systems to run a COBOL program.

2. How does a programmer declare variables in COBOL?

Ans:

Variables in COBOL are declared in the DATA DIVISION, usually within the WORKING-STORAGE section. Each variable is assigned a name, type, and size and is generally referenced within a hierarchical numbering system to refer to structure and association.

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3. What are the applications of COBOL in Business.

Ans:

  • Transaction Processing: It is used most highly in banks and other finance-related applications where transaction volume runs high.
  • Report Generation: It will generate detailed reports for business purposes and decision-making analysis.
  • Legacy System Maintenance: Several organizations still require COBOL to maintain their existing applications and systems.

4. What are the key differences between COBOL and modern programming languages?

Feature COBOL Modern Programming Languages
Syntax Verbose and rigid, focused on readability More concise and flexible syntax
Data Types Limited data types (e.g., numeric, alphanumeric) Rich set of data types, including collections and objects
Object-Oriented Support Limited (primarily procedural) Strong Support for object-oriented programming
Use Cases Primarily used in business and financial applications Wide range of applications, including web, mobile, and data science.
Performance Optimized for batch processing and data handling Performance varies by language and use case, but it often focuses on speed and efficiency.
Community and Support Smaller communities, mainly legacy-focused Large and active communities, rapid evolution and Support for modern development practices.

5. In COBOL, what distinguishes the CALL and LINK statements?

Ans:

  • CALL It is used for invoking a program or subprogram that may exist in different modules or files. It permits independent execution.
  • LINK is Similar to CALL, but it’s typically used for programs in the same executable module; it allows them to share data directly between them.

6. How can COBOL users do dynamic memory allocation?

Ans:

COBOL allows dynamic memory allocation through built-in statements that enable memory allocation at runtime. Alternatively, COBOL can interface with a C or other language to utilize its dynamic memory management functions. Some modern implementations of COBOL, for example, Micro Focus COBOL, offer built-in functions for dynamic memory management so that memory can be allocated and deallocated inside the COBOL program itself more easily.

7. Handling exceptions and errors of COBOL

Ans:

COBOL employs file status codes to inform of success or failure in operations. A programmer may thus use the conditional logic based on these codes to handle errors effectively. Declarations can also be used to define procedures for error handling. Options exist where using the ON ERROR clause is possible in some statements; hence, particular steps may automatically be taken when an error arises in an operation.

8. What is a COBOL paragraph?

Ans:

A block of statements under the same name groups together related statements. A paragraph always has a name and does something different from other paragraphs. Paragraphs can be invoked from the PROCEDURE DIVISION to carry out some action. Such means that parts of a program can be encapsulated into small units of code using meaningful variables within that specific context rather than in a broader context, thus making code much more modulated and easier to read.

9. Identify any three Divisions of COBOL.

Ans:

  • IDENTIFICATION DIVISION: In which the program’s name is specified, etc.
  • ENVIRONMENT DIVISION: In which environment setting is done, including input and output setting.
  • DATA DIVISION: In which all data item definitions are used throughout the program.
  • PROCEDURE DIVISION: In which executable logic and program instructions will be placed.

10. How to dynamically load a table in COBOL?

Ans:

To dynamically load a table in COBOL, one would declare an array that can hold data and then apply file handling techniques to read data from a file or some external source. The logic would involve increasing and decreasing the size and content of the array at runtime to accommodate varying data loads. Additionally, using a loop structure can help efficiently process each record and ensure data integrity during updates.

11. What is the use of the COBOL Code for sequential handling?

Ans:

COBOL code is structured for sequential processing, primarily through file-handling statements. Programs can read data from files in a specific order, process each record in the order it is read, and write output back to files in the same or another order. The sequential nature allows for easy data processing, especially in batch-processing situations. This design simplifies error handling, as issues can be addressed as they arise during the processing sequence.

12. What are datasets, records, and fields?

Ans:

  • Datasets: Files holding files or collections of data, which may or may not be in sequence. Datasets are the input for data within a program.
  • Records: A single entry within a dataset with one or more fields. Each record usually represents a single data unit, such as a customer or transaction.
  • Fields: The most microscopic unit of data contained within a record contains specific information items, such as a name or account number. Fields have defined data types and lengths.

13. What are the Arithmetic expression precedence rules?

Ans:

In COBOL, arithmetic expressions have some precedence rules:

  • Parentheses: The expressions inside the parentheses are applied.
  • Exponents: The exponentiation is applied.
  • Multiplication and Division: Left to right, the respective operations are performed.
  • Addition and Subtraction: These are the last operations and work from left to right.

14. What is an intrinsic function?

Ans:

The intrinsic function in COBOL is a built-in function embedded in the language for performing a specific calculation or operation on data. These functions can manipulate strings, perform mathematical calculations, or convert data types; they add features to the language without writing extra code. By leveraging intrinsic functions, developers can enhance program efficiency and readability while reducing development time.

15. Which types of intrinsic functions are there?

Ans:

  • Mathematical Functions carry out calculations (for example, ABS, SQRT).
  • String Functions Manipulate character strings (e.g., LENGTH, TRIM).
  • Date and Time Functions Manipulate date and time values (e.g., CURRENT-DATE).
  • Conversion Functions Convert the data type of a value (e.g., NUMVAL, STRING).

16. What does ABEND mean?

Ans:

ABEND stands for “abnormal end.” It refers to an unexpected termination of a program or process, often due to errors or exceptions. In COBOL and other mainframe environments, an ABEND indicates that the program could not complete its execution normally, usually triggering an error message and requiring debugging to identify the cause. Resolving an ABEND is crucial for ensuring the stability and reliability of applications in production environments.

17. How do COBOL programming techniques read and write records sequentially?

Ans:

Reads the next record of a file into a defined record structure. If the end of the file is reached, the program can handle this condition gracefully. Writes a record to a file, usually appending to the end or writing to a specified position. These operations are typically enclosed in a loop to process multiple records until the end of the dataset. Proper error handling should also be implemented to manage any issues during the read or write processes, ensuring data integrity.

18. What are the greatest ways to steer clear of ABEND?

Ans:

  • Error Handling: Implement robust error handling using status codes and declarations.
  • Input Validation: Validate data before processing to ensure it meets expected formats and ranges.
  • Code Testing: Regularly test code in various scenarios to identify potential issues.
  • Resource Management: Ensure proper opening and closing of files and management of memory resources.

19. Describe the distinctions between COBOL’s static and dynamic calls.

Ans:

These calls bind the called program at compile time. The program’s place and form are now fixed, which may translate to better Performance but less update flexibility. These calls bind the program at runtime, which gives more flexibility. Changing the called program no longer requires recompilation, but this entails overhead and possible errors when the called program’s interface changes. 

20. What is the purpose of INSPECT in COBOL, and what are some examples of common applications?

Ans:

The INSPECT verb in COBOL is used to scan and format character strings. It can count occurrences of a specific character or character string, replace characters, or change the data format. Examples of common applications include:

  • Counting specific characters to ensure data integrity. 
  • Replacing or formatting specific characters in output reports.
  • Batch operations on strings for simplifying string handling.

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    21. What are the historical origins of COBOL?

    Ans:

    The CODASYL Committee developed COBOL in the late 1950s and early 1960s. It focused on providing a standardized business applications language that could be easily used across different computer systems. Because of its strong relationship with the business community, it was designed to be quite readable and user-friendly.

    22. Why is the COBOL 85 standard significant?

    Ans:

    • Structured programming constructs had been added to the language by including the PERFORM statement and improving flow control support.
    • Further data types such as COMP-5 to achieve Performance in operations
    • Improvements in capabilities related to the manipulation of strings and character data have made COBOL more versatile and powerful for modern applications

    23. What does COBOL provide the facilities for structured programming?

    Ans:

    • Modularization: It makes paragraphs and sections encapsulate code, promoting reusability.
    • Control Structures: It has IF statements and EVALUATE (or switch-case), and it also provides PERFORM for better flow control.
    • Declaratives: This enables the definition of conditions and routines that can more systematically manage program behavior.

    24. Which data types does COBOL provide?

    Ans:

    • Numeric Types: These are for numeric data, such as COMP (binary), COMP-3 (packed decimal), and ordinary numeric.
    • Alphanumeric Types: For character data, including PIC X (character) and PIC A (alphabetic).
    • Decimal Types: For fixed-point decimal numbers so that financial calculations can be accurate.
    • Boolean Types: Introduced in later standards for logical operations. (COBOL 2002 and later).

    25. How to declare a COBOL file?

    Ans:

    Files in COBOL are declared in the ENVIRONMENT DIVISION, more precisely in the INPUT-OUTPUT SECTION. The file’s name, characteristics (organization, access mode), and position relative to the processed data should be given. For example, when defining a sequential file, one must explain the structure of records.

    26. What is the meaning of the WORKING-STORAGE section?

    Ans:

    The WORKING-STORAGE section of COBOL declares variables that hold temporary data during a program’s execution. It stores data items that, following several procedure calls, preserve their values and can be used for calculations, flags, or other intermediate results.

    27. How to perform file handling in COBOL?

    Ans:

    • Opening the file for reading, writing, or updating.
    • Retrieving records from the file.
    • Adding new records to a file.
    • Closing the file: this will release resources and ensure data integrity. 
    • File operations typically involve handling conditions at end-of-file and error checking using file status codes.

    28. What is the difference between an indexed and a sequential file?

    Ans:

    Take advantage of an index so records can be accessed quickly based on key fields. They allow random access, so one does not have to read the entire file if a record needs to be retrieved or updated. Store records in some specific order and are accessed in the same sequence. Records must be read sequentially, so they are good for batch processing but inecould be more for random access.

    29. How to implement sorting in COBOL?

    Ans:

    Sorting in COBOL can be done with the SORT statement. Nominate an input file and an output file and the key fields on which wish to sort the file. COBOL will then sort the file internally based on ascending or descending criteria. It is often a useful preparative step before processing or report generation.

    30. What are the kinds of COBOL loops?

    Ans:

    • PERFORM.THRU: Executes a series of paragraphs or sections sequentially.
    • PERFORM UNTIL: Executes a code block repetitively until a given condition is met.
    • Perform varying: This allows someone to loop using a varying variable that goes through a change in each iteration; this is often necessary when looping over arrays or tables.

    31. How to declare and use arrays in COBOL?

    Ans:

    Arrays are defined in the DATA DIVISION in COBOL with a specific syntax. An array is determined by size and data type and is often located inside the WORKING-STORAGE SECTION. In the example below, could declare to store student grades. They can then reference and manipulate elements of the array using their index positions, allowing them to store and process multiple values efficiently.

    32. What does the PROCEDURE DIVISION do?

    Ans:

    PROCEDURE DIVISION is the module of COBOL where executable statements can be found. It holds the manipulations of data, the calculations for the answers, and the control when the program has to be followed according to the division. This division is an essential part of implementing a program’s functionality, like calling the subprograms and different operations that were defined according to the data in the DATA DIVISION.

    33. How to create a subprogram in COBOL?

    Ans:

    • Define the subprogram in its source file.
    • Include the appropriate IDENTIFICATION DIVISION and DATA DIVISION for the subprogram.
    • Write the logic of the subprogram in the PROCEDURE DIVISION.
    • Use a CALL statement in the main program to call the subprogram and pass any necessary parameters.

    34. What is the purpose of the DATA DIVISION?

    Ans:

    The DATA DIVISION is responsible for all the data items applicable to the program in COBOL. This section specifies the structure, type, and size of data elements, including variables, constants, files, and arrays. This means the program would then clearly understand the data it uses to process it, manage memory, and manipulate data effectively.

    35. What is the way COBOL manipulates a string?

    Ans:

    Strings in COBOL are manipulated through intrinsic functions and special statements. It provides functions such as LENGTH, TRIM, and SUBSTRING to deal with strings. On the other hand, the MOVE statement can be used to copy strings, while the INSPECT verb can search and replace characters within strings, making it possible to do a comprehensive operation on strings.

    36. What does fixed versus free format mean in COBOL?

    Ans:

    • Fixed Format: With traditional COBOL, especially pre-COBOL 2002, the code has to be formatted within certain column positions that can greatly reduce readability and flexibility. It demands careful attention to indentation and spacing.
    • Free Format: The free format was introduced in the later standards and, therefore, allows a more flexible code layout and enables programmers to write code without strict column constraints; this, therefore, means one shall improve readability and maintainability besides supporting modern coding practices.

    37. How are input/output operations performed in COBOL?

    Ans:

    File handling statements carry out input/Output operations in COBOL. The statements include:

    • Opens files to read or write.
    • Reads records from a file.
    • Writes record to a file.
    • Closes the file after all operations are done. 
    • The DISPLAY statement prints any data onto the screen, and the ACCEPT statement receives data input from the user.

    38. What are the benefits of using COBOL for business applications?

    Ans:

    Exceptional Performance in transaction processing with near-zero error rates. A large amount of data can be processed without much effort; hence, it is the most suitable for financial systems and databases. The English-like syntax language makes reading and maintaining easier for those who are not computer programmers. Most organizations still use COBOL for legacy systems, so its proper usage must be retained or updated.

    39. How can COBOL be applied in current technological advancement?

    Ans:

    • Use SOAP or REST APIs to enable COBOL applications to talk to other systems.
    • Use middleware that lets COBOL communicate with Java and .NET applications.
    • Use tools and drivers for interaction with new-generation databases.
    • Migrate COBOL applications to the cloud for scalability and accessibility.

    40. What are the fundamental debug techniques used in COBOL?

    Ans:

    • Use the DISPLAY statement to print variable values at different points in the program to trace execution.
    • Checking file status codes following on from any operations performed to detect defects in file handling
    • Use debuggers capable of supporting breakpoints and step-through execution for tracing program flow.
    • Thorough code review and unit testing primarily focus on detecting logic errors that may have occurred before running the program.

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    41 How to use the EVALUATE statement in COBOL?

    Ans:

    The EVALUATE statement in COBOL is very close to a switch case in other programming languages. It can be used to evaluate and match an expression with the required values or conditions. It can be used when some blocks of code must be executed based on the evaluation result. As of this, it may improve readability and simplify control flow considerably when one has much contention.

    42. What is a COBOL COPYBOOK?

    Ans:

    • A copybook is a reusable COBOL code component that contains common data definitions or procedures. 
    • It is stored in an external file and can be shared by any number of programs using a COPY statement. 
    • This aids in code reuse and favors standardization and consistency to minimize redundancy and simplify maintenance by being at a single point where changes can be made.

    43. How does COBOL handle dates and times?

    Ans:

    COBOL dates and times can be manipulated using intrinsic functions like CURRENTDATE, which inputs the current date and time of the system to the computer. Specific data types are also introduced in COBOL for date and time. There are facilities in COBOL for computing the differences in days between two dates and accepting optional parameters in displaying date values.

    44. What is ACCEPT and DISPLAY Statement?

    Ans:

    This statement reads data from the user or the operating system. It enables a program to capture user input data, making it irreplaceable for interactive applications. This statement is used to display data onto the screen or specific output device. It enables user feedback by displaying results and debugging by showing variable values at run time.

    45. How do users in COBOL manage transactions?

    Ans:

    Ensuring that a group of operations is considered one transaction, thus all the steps are successful or none. Checking the result of executing each file operation to account for errors by rolling back the transactions if necessary. Where applicable, employ database transaction controls to commit the changes based on the success of all the steps or roll back them if not.

    46. What are some common COBOL data validation methods?

    Ans:

    • Field-Level Validation: Data type, length, and format validation at the field level before processing.
    • Range Checks: Whether the numeric values are within some acceptable limits
    • Cross-Field Validation: Consistency check on related fields. For example, a date cannot be a start date after an end date.
    • Using STATUS Codes: For file operations, the results of those operations are validated through status codes for read-write errors.

    47. How do users implement condition handling in COBOL?

    Ans:

    • To test conditional statements and execute blocks of codes if the condition is satisfied.
    • To keep more than one condition in a single statement elegantly.
    • Defining exception handling procedures that are called on certain conditions, so exception handling cases could be maintained centrally.

    48. How can one make COBOL code maintainable?

    Ans:

    • Write programs into subprograms or paragraphs, which can be reused.
    • Comment code with explanations of logic and data structures.
    • Use meaningful and consistent names for variables and data items.
    • Solicit peer reviews that highlight areas of improvement and shortcomings.
    • Have comprehensive testing and debugging practices to establish the reliability of the software.

    49. How does COBOL handle concurrency?

    Ans:

    Most COBOL packages allow synchronization that can lock records in case of an update to avoid conflicts. To handle multiple transactions that run concurrently, use commit and rollback DBMS techniques. Offer methods on queuing or retry operations whenever resources are shared between the two things accessing them to minimize conflicts.

    50. What is the primary distinction and similarity between COBOL and modern programming languages?

    Ans:

    • COBOL has a wordy, English-like syntax, whereas modern programming languages typically favor concise and expressive syntax.
    • COBOL is optimized for processing structured data, particularly in business applications. Modern languages also have many flexible data types and structures (such as objects).
    • COBOL is used in legacy systems and batch processing, but modern programming languages are generally used in web or mobile applications.
    • Whereas modern programming languages usually enable native asynchronous and concurrency capabilities, COBOL typically uses a more sequential execution model.

    51. How does COBOL interact with databases?

    Ans:

    COBOL can interact with databases using SQL (Structured Query Language) via embedded SQL statements or database-specific APIs. This can be done in a program to insert, update, delete, or retrieve data from relational databases. More importantly, COBOL programs use database connectors, such as DB2, so connections and transactions can be processed.

    52. What is the EXIT PROGRAM statement used for?

    Ans:

    The EXIT PROGRAM statement is used to leave a COBOL subprogram and transfer control to the invoking program. It can also return a status code that indicates the subprogram’s completion status, which the invoking program may use to manage the flow of execution based on whether the subprogram’s invocation was successful or caused errors to occur.

    53. Which statements are used for arithmetic operations in COBOL?

    Ans:

    Arithmetic operations in COBOL are performed using the following statements:

    • ADD: add values
    • SUBTRACT: subtract values
    • MULTIPLY: multiply values
    • DIVIDE: divide values. Each of these statements also has an optional operation of GIVING so that the result is to be put in a specific variable.

    54. What is a Level Number in COBOL?

    Ans:

    A Level Number in COBOL is a numeric identifier used to define the hierarchy of data items in the DATA DIVISION. It indicates the relationship among data items, where low numbers indicate higher levels. For instance, an example of a level number is that 01 defines it as a top-level item, while 05 or 10 defines it as a sub-item. This represents data where complicated definitions can be organized.

    55. How does COBOL support modular programming?

    Ans:

    The use of subprograms and paragraphs as tools of modular programming is well supported in COBOL. Subprograms enable encapsulation of logic, hence divided units, which may be called from several programs and are thus reusable. Besides, COMMON data definitions in COPY books support modularity while reducing redundancy.

    56. What is a LINKAGE SECTION used for?

    Ans:

    The LINKAGE SECTION is a part of the COBOL program definition and is used to declare items of data being passed between programs, especially those subprograms. This allows the calling program to pass variables to the called subprogram, allowing data to be passed around without duplicated definitions. This eliminates duplication and makes it easy to share information between programs, and memory is utilized efficiently.

    57. How to manipulate files in COBOL using SORT and MERGE?

    Ans:

    • SORT: This statement can sort records on a file. It specifies an input file, an output file, and one or more sort keys. The sort is done in memory and written to the output file.
    • MERGE: The MERGE statement combines multiple pre-sorted files into a single output file, preserving the order of the records based on the keys specified. It is very useful for consolidating data from various sources.

    58. What are the benefits of using COBOL for batch processing?

    Ans:

    • Efficiency: It can process large volumes of data. So, this makes COBOL suitable for batch jobs.
    • Data Handling: Its robust data manipulation capabilities efficiently manage intricate data structures.
    • Reliability: To date, its tendency to cause transaction errors in the processing of the most critical commercial transactions has never been documented.
    • Compatibility: Most legacy systems are still running on COBOL and can, hence, be integrated into existing batch processes without any hitch.

    59. How does COBOL address the question of error handling in file operations?

    Ans:

    For any file operation-COMMIT, UNLINK, READ or WRITE program checks the file status code to know if an error had happened during the last file operation execution. According to the status code, the program may apply some conditional logic and then take appropriate measures, such as retrying the action, committing further, or logging an error.

    60. What are the kinds of data files in COBOL?

    Ans:

    • Sequential Files: Records are stored in sequence order and accessed one after the other.
    • Indexed Files: An index allows random access to records more quickly.
    • Relative Files: Access records based on relative positions rather than specific keys.
    • VSAM Files: Virtual Storage Access Method files are highly performing files for data access and management.
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    61. How can COBOL applications be optimized for Performance?

    Ans:

    • Using suitable data structures for the task.
    • Minimizing the number of file accesses by buffering records as much as possible.
    • Optimizing algorithms for processing or sorting of data.
    • Utilizing compiler optimization and options for performance tuning.

    62. What is a data structure in COBOL, and how is it defined?

    Ans:

    A data structure in COBOL is a method of arranging related data items. It can be defined in the DATA DIVISION using a combination of level numbers and data types. For instance, a record can have fields containing different data items like customer name, address, and account number, defined hierarchically with level numbers to indicate relationships.

    63. How to read and write data using VSAM files in COBOL?

    Ans:

    • Open the VSAM file for input or output.
    • READ statement reads records from the VSAM file, giving either the key or a relative record number.
    • WRITE statement is used to add new records or to update existing ones.
    • Close the file after finish all your operations. According to the status codes, properly handle your errors.

    64. What are the security features available in COBOL?

    Ans:

    Control folder permissions that restrict access to some sensitive information. COBOL does not maintain encryptions but can rely on other systems offering encryption for data in transit or at rest. Implement a logging mechanism to monitor access and changes to data to meet compliance requirements and complete the security audit.

    65. How is COBOL designed for networking?

    Ans:

    • APIs and Middleware: Use APIs and middleware to communicate across networks.
    • Embedded SQL: SQL is used to access the database over a network. This will enable remote databases for COBOL applications.
    • Web Services: Applications written in COBOL can now communicate over the internet, thus enabling web services.

    66. What is a file status code and its purpose?

    Ans:

    A file status code is a two-character code used in COBOL to indicate the return status from a file operation. It is checked after an operation, like READ, WRITE, or OPEN, to determine whether the operation was successful (e.g., the code ’00’) or if there was an error (e.g., ’10’ for end-of-file). The program will then take appropriate actions based on the status code.

    67. How do conditional processing in COBOL?

    Ans:

    • IF Statement: The IF statement evaluates a condition and executes a block of code based on whether the condition is true or false. It can be simple or compound, allowing for multiple conditions using AND or OR operators.
    • EVALUATE Statement: This construct functions like a switch-case statement in other languages, allowing for multi-way branching. It evaluates an expression and executes the corresponding block of code for the first matching condition. 
    • PERFORM with Conditions: The PERFORM statement can be used to execute paragraphs or sections based on conditions. Can conditionally call procedures, enhancing code modularity and reusability.

    68. What is the MULTIPLY statement in COBOL?

    Ans:

    A multiply statement performs multiplication on one or more operands and places the product in a variable designated. The statement can optionally include directives, including GIVING to output the result to a specific variable. The MULTIPLY statement can also handle multiple operands, allowing for complex calculations in a single line, and it supports both numeric and packed decimal data types for enhanced flexibility in arithmetic operations.

    69. What ways are there to test COBOL programs effectively?

    Ans:

    • Unit Testing: Test each component or module individually.
    • Integration Testing: Test several modules together.
    • Test Cases: Describe test cases for different aspects. Above all, include edge-case scenarios.
    • Automated Testing Tools: Use any tool to automate the testing process to save time.

    70. What does the DISPLAY verb do in debugging?

    Ans:

    A very crucial verb in debugging is DISPLAY. It allows the developer to output variable values, messages, and program states to the console or a given output device. Strategically placed in the code, a programmer can trace execution flow, identify variable values at specific points, and, during development, trace or diagnose issues.

    71. How to handle variable-length records in COBOL?

    Ans:

    The definition of variable-length record in COBOL is achieved by specifying the record layout in the DATA DIVISION using the FILE SECTION. The RECORDING MODE should be defined as F for fixed or V for variable length. The common practice is to have a field at the beginning of the record that stores the length of the record itself. This allows flexible handling of records where size can change, so the application handles differences in data inputs well.

    72. What are the COMP and COMP-3 data types?

    Ans:

    • In this regard, the COMP data type in COBOL is a numeric binary type that holds numeric values and, therefore, provides efficient arithmetic calculations. Its size depends on the implementation but is usually 2, 4, or 8 bytes.
    • The COMP format also proves beneficial for systems applications, mainly in financial systems, due to its ability to retain decimal precision, unlike decimal formats, which add a byte.
    • COMP-3 may lead to compressed files and faster processing. However, it must be handled properly during computation or conversion.

    73. How are recursive subprograms implemented using COBOL?

    Ans:

    • Using COBOL, recursive subprograms are implemented by declaring a subroutine that can call itself.
    • Well-defined base case conditions must exist to avoid infinite recursion, and the function should ultimately terminate.
    • The recursive logic should be enclosed in the PROCEDURE DIVISION of the subprogram to take proper care of its input and output.
    • The state of each recursive call should be tracked. This may be done through parameters or global variables.
    • Procedure divisions with recursion are very tough to debug. Therefore, proper design and testing are crucial.

    74. What are the consequences of COBOL’s fixed-point arithmetic?

    Ans:

    • The fixed-point arithmetic within COBOL does deliver an exact outcome and monitors the number of decimal positions included in number types.
    • There are no rounding errors due to floating-point arithmetical. Hence, it is satisfactory for high-precision applications such as financial transactions. 
    • The fixed arithmetic may lead to a constrictive range of values possible, particularly where very large and very small values are concerned. Care must be taken to ensure that the scale and precision are manageable and that they could cause either overflow or underflow. 

    75. What is the effect of nesting IF statements within each other in COBOL? 

    Ans:

    • Nested IF statements are permitted in COBOL so that an IF statement can be placed inside another. 
    • This enables complex decision-making to be based on a set of conditions. 
    • Nested IFs also must end with matching.

    76. What is a pointer in COBOL, and how to use one?

    Ans:

    A pointer in COBOL is a variable whose address contains the address of another variable, therefore allowing direct access to data in memory. Pointers are extremely useful when managing complex data structures, such as linked lists or dynamic arrays. They allow the programmer to traverse and manipulate such structures with a minimal overhead of copying data.

    77. How can search functionality be added to COBOL? 

    Ans:

    Search functionality in COBOL can be implemented by applying the SEARCH statement with an efficient lookup of particular values in the table. State the table and the key fields they wish to search against. This SEARCH statement will iterate through the table until a match is located based on the stipulated condition. Once located, other operations like fetching or processing related data can be performed. This procedure is optimum for handling large datasets due to minimal use of human iteration.

    78. What is the purpose of the INITIALIZE statement?

    Ans:

    • The INITIALIZE statement is essential in COBOL programs because it initializes data items with their default initial values. For numeric fields, it is filled with zero, and for alphabetic fields, spaces are put inside them.
    • This adds to the reliability of codes by preventing errors due to uninitialized data while ensuring that all variables appear in known states. Using the INITIALIZE statement reduces errors based on garbage values and decreases debugging time by eliminating possible runtime errors.
    • It is very useful in long programs where tracing the state of many variables is difficult. Consistent use of this statement promotes good programming practice.

    79. How does COBOL manage the memory allocation?

    Ans:

    • COBOL manages memory allocation primarily with definitions in the DATA DIVISION where variables get memory assigned to them at compile time.
    • Static data item sizes are figured from their definitions, and memory is reserved for them.
    • Dynamic memory allocation is quite applicable in COBOL, either through an interface to the language C or through intrinsic functions. This is useful, especially if arrays or other complex structures are interesting.
    • Proper use of memory management would prevent leaks and avoid effective resource consumption. 

    80. What does the RETURN-CODE variable accomplish? 

    Ans:

    The RETURN-CODE variable in COBOL is a status indicator that captures the completion status of a program or subprogram. It is set to a numeric value usually defining if the execution was effective or an error occurred. By checking this variable, calling programs may decide the outcome of the called program. For example, a value of ‘0’ may indicate success, whereas other values indicate different forms of errors.

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    81. How to enhance the Performance of accessing a COBOL file?

    Ans:

    Several approaches to optimizing COBOL file access can be identified. Indexed files can actually speed up data retrieval when using keys, allowing direct access to the records using their values. Other approaches include reducing I/O operations through the buffering of records to reduce requests made on the disk, which reduces efficiency performance. Efficiency will also be served by the application’s access patterns when efficient methods of organizing files are used, that is, by a serial or relative file structure.

    82. What are some common options for COBOL compilers?

    Ans:

    • Some of the most common COBOL compiler options control optimization, debugging operations, or data management.
    • The optimization level may be made more aggressive to improve runtime Performance, and debugging options permit to log variable states and execution paths to a very detailed degree.
    • Even some more specific compiler options might involve managing memory allocation or managing data types and structures.
    • Developers can further optimize these for good Performance and maintainability of their COBOL programs. Knowing how to leverage these is a key aspect of good COBOL programming.

    83. How would one document COBOL code?

    Ans:

    Good practices for documenting COBOL code involve writing meaningful comments throughout the code that describe complicated logic and the purpose of variables and procedures. A uniform naming convention for variables and data structures makes it easier to understand what the program is doing just by looking at the code. Documentation should be updated frequently as the code is changed to keep it useful 

    84. What does the UNSTRING statement do?

    Ans:

    The UNSTRING statement in COBOL divides one string into more substrings by delimiters specified. The UNSTRING statement allows a programmer to take the data in one variable and break it into distinct parts, which are then assigned to separate fields. This is often useful where input data comes through in a combined format, such as user input or CSV files. The syntax specifies the source string, the target variables, and the delimiters that determine where the string should be split.

    85. How do apply user-defined functions in COBOL? 

    Ans:

    • User-defined functions in COBOL are applied by developing a subprogram that holds special logic or calculations.
    • COBOL supports using CALL BY VALUE and CALL BY REFERENCE for arguments, which provides flexibility in how data is passed.
    • The RETURNING clause must accompany the subprogram if the return value is expected. Modules that create functions are written so that they will be easy to maintain. 
    • Better documentation and comments on each function are easier for other developers to make in this regard and are clear.

    86. What is the difference between CALL BY VALUE and CALL BY REFERENCE?

    Ans:

    • CALL BY VALUE in COBOL refers to passing a copy of the variable’s value to the subprogram. Any changes to this parameter in the subprogram will not affect the original variable.
    • This technique is used when want to preserve the integrity of the actual data. In contrast, CALL BY REFERENCE actually passes the address of the variable; this way, a modification done on the subprogram directly alters the actual variable.
    • This may result in more efficient memory usage, but it needs to be handled with care lest such side effects occur inadvertently. Knowing the implications of each technique becomes essential to designing one’s program effectively.

    87. How does COBOL handle floating-point arithmetic?

    Ans:

    COBOL supports floating-point arithmetic through specific data types, such as COMP-1 and COMP-2, representing single and double precision. The types, therefore, can represent very large or small numbers and find applications mainly in scientific and engineering calculations. COBOLL’s floating-point operations follow IEEE standards. However, there are often opportunities to commit an error in making proper use of precision or rounding off floating-point arithmetic to introduce calculation errors.

    88. Advantages of using COBOL with legacy systems.

    Ans:

    • The most evident advantages of COBOL with legacy systems are their robustness and stability.
    • COBOL has been widely used as a programming language in several thousand business applications, and the majority of existing legacy systems are based on COBOL; thus, these systems help organizations exploit the pre-existing codes and minimize re-coding effort. 
    • Second, COBOL’s ability to process a huge amount of data makes it best suited for transaction processing in legacy systems. It also benefits from good data integrity and reliability, which are important in financial and operational applications. 

    89. How can users do batch updates in COBOL? 

    Ans:

    • Batch updates can be done by reading a file of records, applying the changes as needed, and then writing them back into the same file or to a new file. It involves opening the input file in INPUT mode and the output file in OUTPUT mode.
    • COBOL has made file-handling capabilities available, enabling efficient processing for large datasets. Using an iterative structure, one would read each row, apply logic to determine what to update, and then write out the changes.
    • This will allow massive data to be handled in one operation and reduce the amount of time required for updating. The approach should also consider handling errors during the update process.

    90. What is the FuFutureold for COBOL in software development?

    Ans:

    The software industry has bright prospects for the future of COBOL, particularly in the banking, finance, and government sectors, where legacy systems dominate. Many organizations rely on their systems for critical missions; hence, the need for maintenance and modernization continues unabated. Another key reason for the popularity of COBOL skills is that companies have plans to integrate COBOL with other emerging technologies, including the cloud and APIs. An important step in countering the skills gap resulting from the aging of the population is to train new developers for COBOL.

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