user define function in c

To define a user-defined function in C, you need to follow these steps:

Step 1: Function Declaration Declare the function by specifying its return type, name, and parameters (if any). The function declaration should be placed before the main function or any other function that calls it.

Step 2: Function Definition Define the function by providing the implementation of the function body. This includes the statements and logic that will be executed when the function is called.

Step 3: Function Call To use the user-defined function, you need to call it from another function. Simply write the function name followed by parentheses and any necessary arguments.

Here is an example that demonstrates these steps:

#include <stdio.h>

// Step 1: Function Declaration
int addNumbers(int a, int b);

int main() {
    int num1 = 5, num2 = 10, sum;

    // Step 3: Function Call
    sum = addNumbers(num1, num2);

    printf("Sum = %d", sum);

    return 0;
}

// Step 2: Function Definition
int addNumbers(int a, int b) {
    return a + b;
}

In this example, we define a user-defined function called addNumbers that takes two integer parameters a and b and returns their sum. We declare the function before the main function, and then define it after the main function. Finally, we call the addNumbers function from the main function and print the result.

This is a basic illustration of how to define and use a user-defined function in C. You can modify the function declaration, definition, and call based on your specific requirements.