C Program to Find Power of a Number

You can find the power of a number in C by using a loop to multiply the base number by itself exponent times, like for (int i = 1; i <= exponent; i++) result *= base;.

Examples

Inputbase = 2, exponent = 3

Output8

Inputbase = 5, exponent = 0

Output1

Inputbase = 3, exponent = 4

Output81

How to Think About It

To find the power of a number, think of multiplying the base number by itself as many times as the exponent says. If the exponent is zero, the result is always 1. So, start with 1 and multiply by the base repeatedly until you reach the exponent count.

Algorithm

1

Get the base number and exponent from the user.

2

Initialize a result variable to 1.

3

Repeat multiplying the result by the base, exponent number of times.

4

After the loop ends, the result holds the power value.

5

Print the result.

Code

c

#include <stdio.h>

int main() {
    int base, exponent, result = 1;
    printf("Enter base and exponent: ");
    scanf("%d %d", &base, &exponent);
    for (int i = 1; i <= exponent; i++) {
        result *= base;
    }
    printf("%d to the power %d is %d\n", base, exponent, result);
    return 0;
}

Output

Enter base and exponent: 2 3
2 to the power 3 is 8

Dry Run

Let's trace base=2 and exponent=3 through the code

1

Initialize result

result = 1

2

First loop iteration

result = 1 * 2 = 2

3

Second loop iteration

result = 2 * 2 = 4

4

Third loop iteration

result = 4 * 2 = 8

5

Loop ends

result = 8

Iteration	result
0 (initial)	1
1	2
2	4
3	8

Why This Works

Step 1: Start with result = 1

We use 1 because multiplying by 1 does not change the value and it is the identity for multiplication.

Step 2: Multiply result by base repeatedly

Each loop multiplies the current result by the base, building up the power step by step.

Step 3: Loop runs exponent times

This ensures the base is multiplied by itself exactly exponent times, giving the correct power.

Alternative Approaches

Using recursion

c

#include <stdio.h>

int power(int base, int exponent) {
    if (exponent == 0) return 1;
    return base * power(base, exponent - 1);
}

int main() {
    int base, exponent;
    printf("Enter base and exponent: ");
    scanf("%d %d", &base, &exponent);
    printf("%d to the power %d is %d\n", base, exponent, power(base, exponent));
    return 0;
}

Recursion is elegant but can be less efficient and uses more memory due to function calls.

Using math.h pow() function

c

#include <stdio.h>
#include <math.h>

int main() {
    double base, result;
    int exponent;
    printf("Enter base and exponent: ");
    scanf("%lf %d", &base, &exponent);
    result = pow(base, exponent);
    printf("%.2lf to the power %d is %.2lf\n", base, exponent, result);
    return 0;
}

Using pow() is simple and handles floating-point numbers but requires including math.h and linking math library.

Complexity: O(n) time, O(1) space

Time Complexity

The loop runs exponent times, so the time grows linearly with the exponent.

Space Complexity

Only a few variables are used, so space is constant regardless of input size.

Which Approach is Fastest?

Using the built-in pow() function is fastest and handles more cases, but the loop method is simple and clear for integers.

Approach	Time	Space	Best For
Loop multiplication	O(n)	O(1)	Simple integer powers
Recursion	O(n)	O(n)	Learning recursion, small exponents
math.h pow()	O(1)	O(1)	Floating-point and complex powers