Functions and Recursion in C Programming

 

             Functions and Recursion in C Programming  

  Introduction to Functions

A function is a self-contained block of statements that performs a specific task. Functions allow you to break your code into manageable parts, making it more readable and easier to debug.

    Key Advantages:

• Code Reusability

• Better Readability

• Easier Maintenance

• Reduces Redundancy

 Types of Functions

 In C, functions are categorized into two main types:

1. Library Functions: Built-in functions provided by C libraries (e.g., printf(), scanf(), strlen()).

2. User-defined Functions: Functions created by the user to perform specific tasks.

Function Declaration, Definition, and Call

•  Function Declaration (Prototype):

   A function must be declared before it is used. This tells the compiler about the function's name, return type, and parameters.

                 int add(int, int); // Function prototype

• Function Definition:

This is where the actual logic of the function is written.

int add(int a, int b) {

    return a + b;

}

Function Call:

A function is called by its name followed by parentheses.

int sum = add(5, 10);  // Function call

Parameter Passing

C supports two methods of passing parameters:

1. Call by Value - Copies the actual value of an argument into the function's formal parameter.

2. Call by Reference - Copies the address of an argument into the formal parameter.

// Call by Value example

void updateValue(int x) {

    x = 100;  // This change is local to the function

}

// Call by Reference example

void updateValueRef(int *x) {

    *x = 100;  // This change affects the original variable

}

Recursive Functions

A recursive function is a function that calls itself during its execution. Recursion allows problems to be solved in a more straightforward manner, especially problems that can be divided into similar sub-problems.

Example

int factorial(int n) {

    if (n <= 1) return 1;

    else return n * factorial(n - 1);

}

// Usage:

int result = factorial(5); // Output: 120