In this article, we will write a C program to find the power of a number without using the pow() function. The program takes the number and exponent from the user as input, calculates its power and prints the result on the output window.
Sample Example:
Enter base and power: 5 3 5^3 = 125 Enter base and power: 10 0 10^0 = 1
In C programming, we generally use the built-in pow() function to calculate the power of a number.
But In this program, we don’t want to use any built-in function. Instead, we will build our own logic to calculate the power of a given number.
The power of a number refers to the exponent to which the number is raised. In programming languages, it is generally denoted by the “^” or “**” symbol.
For example, 5^3 represents 5 raised to the power 3 and it is calculated as:
5^3 = 5*5*5 = 125
So, in general, if we want to calculate a raised to the power b, we can write it as:
a^b = a*a*a.....b times
If you pay enough attention to the above expression, you will find out that it represents a loop in the context of programming languages. Which means, that to calculate a raised to the power b, we can multiply a by itself b times which can be achieved using a for/while loop.
Let’s use a simple for loop to calculate the power of a given number:
// C program to calculate the power of a number
// without using the pow() function
#include <stdio.h>
#include <conio.h>
int main() {
int num, pow, result = 1;
printf("Enter base and power: ");
scanf("%d %d" , &num, &pow);
// Calculate num^pow
for(int i = 0; i < pow; i++){
result = result * num;
}
// Print the result
printf("%d^%d = %d", num, pow, result);
return 0;
}
Output:
Enter base and power: 10 3 10^3 = 1000
In this example, the for loop runs pow times to calculate the power of the number.
2. Using a While Loop to Calculate the Power of a Number
We can also use a while loop to calculate the power of a number without using the built-in pow() function.
In this approach, we will copy the value of the pow into a temporary variable count and run the while loop until count becomes zero. Don’t forget to reduce count by -1 on each iteration of the while loop to avoid an infinite loop.
// C program to calculate the power of a number
// without using the pow() function
#include <stdio.h>
#include <conio.h>
int main() {
int num, pow, result = 1, count;
printf("Enter base and power: ");
scanf("%d %d" , &num, &pow);
// Copy the value of pow into count variable
count = pow;
// Calculate num^pow
while(count != 0){
result = result * num;
count--;
}
// Print the result
printf("%d^%d = %d", num, pow, result);
return 0;
}
Output:
Enter base and power: 6 3 6^3 = 216
3. Using Recursion to Calculate the Power of a Number
In programming, recursion is a concept where a function calls itself again and again until a base case is reached. In each function call, the problem is divided into a smaller problem and it continues until the base condition is reached.
In calculating the power of a number, the base case is the power 0. This is because, if any number is raised to the power of 0, its result is always 1.
So, we will create a function power() which takes the base number and power as its arguments and in each function call we will reduce the power by 1 until it becomes 0.
As soon as the power becomes 0, the function will stop calling itself and start backtracking to calculate the result.
See implementation in the following program:
// C program to calculate the power of a number
// without using the pow() function
#include <stdio.h>
#include <conio.h>
// Recursive function
int power(int num, int exp){
// Base case
if(exp == 0){
return 1;
}
return num*power(num, exp - 1);
}
int main() {
int num, exp, result;
printf("Enter base and power: ");
scanf("%d %d" , &num, &exp);
// Calculate num^exp
result = power(num, exp);
// Print the result
printf("%d^%d = %d", num, exp, result);
return 0;
}
Output:
Enter base and power: 5 4 5^4 = 625
In this program, the recursive function power() will continue calling itself until exp becomes zero. As soon as the value of exp becomes 0, it stops calling itself, and backtracking starts.
I hope you will find this article helpful. Thanks for reading.
