A function is a self-contained block of statements that perform a particular task.

# Types

1. **Standard Function**

2. **User Defined Function**

# Standard function
These are pre-defined functions that are already present in the compiler and cannot be edited.

Examples: `printf` and `scanf`

# User-defined functions
These functions are defined by the user.


# Advantages of functions:

1. Reduces the length of the program
2. Easy to debug the program
3. Uses a top-down modular programming approach
4. Functions can be used by many other programs


## User-defined functions can be of four types 

1. Functions without parameters or return values  
2. Functions with parameters and without return values 
3. Functions without parameters and with return values. 
4. Functions with parameters and return values. 



#include<stdio.h>

// Function
int DoubleTheNumber ( int number ){
  int temp = number + number;
  return temp;
}

int main() {
  // calling function
  int val = DoubleTheNumber(10);
  printf("The number is : %d\n", val);
  return 0;
}


What are functions in C?

Types

Standard function

User-defined functions

Advantages of functions:

User-defined functions can be of four types