PHP Program to Find Power of Number

In PHP, you can find the power of a number using the built-in function pow(base, exponent) or by using a loop to multiply the base number repeatedly.

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, you multiply the base number by itself as many times as the exponent says. For example, 2 to the power 3 means 2 × 2 × 2. You can do this by using PHP's built-in pow function or by writing a loop that multiplies the base repeatedly.

Algorithm

1

Get the base number and exponent from the user or input.

2

If using a loop, start with a result of 1.

3

Multiply the result by the base number repeatedly, as many times as the exponent.

4

Return or print the final result.

Code

php

<?php
$base = 2;
$exponent = 3;
$result = pow($base, $exponent);
echo "Result: $result";
?>

Output

Result: 8

Dry Run

Let's trace the example where base=2 and exponent=3 using the pow function.

1

Set base and exponent

base = 2, exponent = 3

2

Calculate power

result = pow(2, 3) which means 2 × 2 × 2

3

Output result

Print 'Result: 8'

Step	Operation	Value
1	Set base	2
2	Set exponent	3
3	Calculate pow(2,3)	8
4	Print result	Result: 8

Why This Works

Step 1: Using pow function

The pow(base, exponent) function calculates the base raised to the power of the exponent directly.

Step 2: Multiplying repeatedly

If you use a loop, you multiply the base by itself exponent times to get the same result.

Step 3: Outputting the result

The final number is printed using echo to show the power calculation.

Alternative Approaches

Using a for loop

php

<?php
$base = 2;
$exponent = 3;
$result = 1;
for ($i = 0; $i < $exponent; $i++) {
    $result *= $base;
}
echo "Result: $result";
?>

This method manually multiplies the base repeatedly and is useful if you want to understand the process without built-in functions.

Using recursion

php

<?php
function power($base, $exponent) {
    if ($exponent == 0) return 1;
    return $base * power($base, $exponent - 1);
}
$result = power(2, 3);
echo "Result: $result";
?>

This method uses a function that calls itself to calculate power, which is elegant but can be less efficient for large exponents.

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

Time Complexity

Using the built-in pow() function is optimized internally, but a loop multiplies the base n times, so it is O(n).

Space Complexity

The program uses a fixed amount of memory regardless of input size, so space complexity is O(1).

Which Approach is Fastest?

The built-in pow() function is fastest and recommended; loops and recursion are slower but good for learning.

Approach	Time	Space	Best For
Built-in pow()	O(1) or optimized	O(1)	Fastest and simplest
For loop	O(n)	O(1)	Understanding multiplication process
Recursion	O(n)	O(n)	Elegant code but uses more memory