Basic C Programming Examples for Beginners

Variables and Data Types

• Definition: A variable is a named memory location used to store data that can be modified during program execution.
• Declaration: Must be declared before use with a specific data type.

Example: int age;

• Naming Rules: Must begin with a letter or underscore (_). Can contain letters, digits, and underscores. Cannot use keywords or special characters.
• Initialization: Variables can be assigned a value at the time of declaration.

Example: int age = 25;

• Scope: Determines the part of the program where the variable can be accessed (local, global, etc.)
• Lifetime: The duration during which a variable exists in memory.



Data Types in C

Basic (Primitive) Data Types:

• int – Integer numbers (e.g., 1, -10)
• float – Single-precision decimal numbers (e.g., 3.14)
• double – Double-precision decimal numbers
• char – Single character (e.g., ‘A’)

Derived Data Types:

• Arrays
• Pointers
• Structures
• Unions
• Enumeration (enum): Used to define a set of named integer constants
• Void Type: Represents “no value”; used for functions that return nothing
• Type Modifiers: short, long, signed, unsigned – used to change the size or sign of data types




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If-else and Switch Cases

Conditional statements control the flow based on conditions.

If-else Example:

• #include
• int main() {
• int marks = 70;
• if (marks >= 90)
• printf(“Grade: A\n”);
• else if (marks >= 75)
• printf(“Grade: B\n”);
• else
• printf(“Grade: C\n”);
• return 0;
• }

Switch Case Example:

• #include
• int main() {
• int choice = 2;
• switch (choice) {
• case 1: printf(“Start\n”); break;
• case 2: printf(“Stop\n”); break;
• default: printf(“Invalid\n”);
• }
• return 0;
• }






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Loops: for, while, do-while

Loops repeat blocks of code.

For Loop:

• for (int i = 1; i <= 5; i++) {
• printf(“%d “, i);
• }

While Loop:

• int i = 1;
• while (i <= 5) {
• printf(“%d “, i);
• i++;
• }



Do-While Loop:

• int i = 1;
• do {
• printf(“%d “, i);
• i++;
• } while (i <= 5);

Output for all:

1 2 3 4 5



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Arrays and Strings

Arrays store multiple values of the same type.

Array Example:

• #int nums[5] = {1, 2, 3, 4, 5};
• for (int i = 0; i < 5; i++) {
• printf(“%d “, nums[i]);
• }

String Example:

• char name[] = “Alice”;
• printf(“Hello, %s\n”, name);

Strings are arrays of characters terminated with \0.




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Functions and Recursion

Functions and Recursion modularize code for reusability and clarity.

Function Example:

• int add(int a, int b) {
• return a + b;
• }
• int main() {
• printf(“Sum: %d\n”, add(3, 4));
• return 0;
• }

Recursion Example:

• int factorial(int n) {
• if (n == 0) return 1;
• return n * factorial(n – 1);
• }
• int main() {
• printf(“Factorial: %d\n”, factorial(5));
• return 0;
• }




Conclusion

The Flood Fill algorithm is a powerful tool in computer graphics, from simple shape coloring to complex region analysis. While the recursive approach is easy to implement, the iterative method is preferred for robustness and performance. Understanding the principles of neighborhood traversal, color replacement, and boundary handling equips you to use this algorithm in a wide range of applications from gaming to image analysis. Whether you’re building a paint application or a grid-based puzzle solver,Pseudocode mastering flood fill gives you a strong foundation in both graphics and algorithmic logic.