Functions in C Programming

Study Notes

Functions in C

A function is a reusable block of code that performs a specific task, consisting of a name, input parameters, and a return value.
Functions help in reducing code redundancy and improving program structure.
Function declaration defines the prototype; function definition provides the implementation.
Example of a simple function that adds two integers:
```
int addition(int a, int b) {
    return a + b;
}
```

Properties and Advantages of Functions

Each function has a unique name to be called from the main() function.
Functions perform specific tasks and can return values to the calling program.
Benefits include top-down programming structure, easier debugging, improved program clarity, and simplified testing.

Categories of User Defined Functions

No arguments, no return values: Functions that do not take inputs and do not return values.
```
void printmsg() {
    printf("Hello !I Am A Function.");
}
```
With arguments, no return values: Functions that accept input but do not return a value.
```
void add(int a, int b) {
    printf("The sum = %d", (a + b));
}
```
With arguments and return values: Functions that accept inputs and return results to the calling function.

Nested Functions

Nesting occurs when a function calls another function within its body.
Example structure:
```
void Function1() {
    Function2();
}
```

Recursion

Recursion refers to a function calling itself directly or indirectly, making local copies of variables for each call until a base condition is met.
Rules:
- Must have a base case to avoid infinite recursion.
- Must progress towards the base case on each call.

Example: Factorial Function Using Recursion

int fact(int n) {
    if (n == 0 || n == 1) return 1; // Base case
    return n * fact(n - 1); // Recursive case
}

For input 5, output is 120.

Comparison: Recursion vs Non-Recursion

Recursion simplifies certain algorithms (like traversing data structures) but can be less efficient due to overhead.
Non-recursive solutions are often iterative and may use less memory.

Description

This quiz covers the fundamentals of functions in C programming, exploring their properties, advantages, and categories of user-defined functions. Gain a deeper understanding of function declaration, definition, and how they enhance program structure and clarity.