C Programs

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Functions in C

Function to subtract two numbers

Introduction

In C programming, using functions helps organize and reuse code.
This program demonstrates how to subtract two numbers using a user-defined function that accepts arguments and returns the result to the main function.

C Program: Function to subtract two numbers

Method 1: The function with int return type (With Arguments, With Return)

#include <stdio.h>
 
// Function declaration
int subtract(int a, int b);
 
int main() {
    int num1, num2, result;
 
    // Taking input from user
    printf("Enter first number: ");
    scanf("%d", &num1);
    printf("Enter second number: ");
    scanf("%d", &num2);
 
    // Function call
    result = subtract(num1, num2);
 
    // Display result
    printf("Difference between %d and %d is: %d\n", num1, num2, result);
 
    return 0;
}
 
// Function definition
int subtract(int a, int b) {
    return a - b;
}

 
OUTPUT :
Enter first number: 25
Enter second number: 10
Difference between 25 and 10 is: 15

Description

1. Function Declaration:
   int subtract(int a, int b); tells the compiler that the function accepts two integers and returns an integer.
2. Function Definition:
   The function computes the difference between a and b using a - b.
3. Function Call:
   main() calls the function and stores the returned result in the variable result.
4. Output Display:
   The result is printed using printf().

C Program: Function to subtract two numbers

Method 2: The function with void return type (With Arguments, No Return)

#include <stdio.h>
 
// Function declaration
void subtractNumbers(int a, int b);
 
int main() {
    int num1, num2;
 
    // Taking input from user
    printf("Enter first number: ");
    scanf("%d", &num1);
    printf("Enter second number: ");
    scanf("%d", &num2);
 
    // Function call
    subtractNumbers(num1, num2);
 
    return 0;
}
 
// Function definition
void subtractNumbers(int a, int b) {
    int difference = a - b;
    printf("Difference between %d and %d is: %d\n", a, b, difference);
}

 
OUTPUT :
Enter first number: 50
Enter second number: 20
Difference between 50 and 20 is: 30

Description

1. Function Declaration:
   void subtractNumbers(int a, int b); — defines a function that takes two integer arguments but returns no value.
2. Function Definition:
   Performs subtraction (a - b) and directly displays the result.
3. Function Call:
   The main() function passes user inputs (num1, num2) to subtractNumbers().
4. No Return Statement:
   Since the function is of type void, it does not return any value to main().