C Program to Find Power of a Number Using Function

We will write a C program to find the power of a number using a function. First, we will use the pre-defined function pow(), and later we will develop a user-defined function.

C program to find the power of a number using pow() function

In C language, the pow() is a pre-defined function that is used to calculate the power of the number. It takes two arguments. It is defined in the header file “math.h”. SO, to use the pow() function, we must include this header file in our program.

Function prototype:- pow(x,y);

The function pow() calculates the power of y. If the x is negative, y must be an integer. If the x is zero, y must be a positive number.

#include<stdio.h>
#include<math.h>
int main()
{
  int num1, num2;

  printf("Enter base and power: ");
  scanf("%d %d",&num1, &num2);

  printf("Result = %.2f",pow(num1, num2));

  return 0;
}

Output for the different test-cases:-

Enter base and power: 2 5
Result = 32.00

Enter base and power: 5 4
Result = 625.00

Using a user-defined function

We can also write a C program to find the power of a number without using pow(). In the below program power() is a user-defined function that calculates the power of a number. Previously we have already written a program to find the power of a number using loops. Based on that program we can write the same using function.

Prerequisites for this program:- Introduction to Function in C, User-defined Functions in C, C Program Using Functions Example

#include<stdio.h>
long power(int a, int b);

int main()
{
  int num1, num2;

  printf("Enter base and power: ");
  scanf("%d %d",&num1, &num2);

  long result = power(num1, num2);
  printf("The result = %ld", result);

  return 0;
}

// User-defined function to calculate power
long power(int a, int b)
{
  long result = 1;
  for(int i=1; i<=b; i++)
  {
    result *= a;
  }
  return result;
}

Output for the different test-cases:-

Enter base and power: 3 3
The result = 27

Enter base and power: 7 2
The result = 49

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