Example 1: Calculate power of a number using a while loop
class Main {
public static void main(String[] args) {
int base = 3, exponent = 4;
long result = 1;
while (exponent != 0) {
result *= base;
--exponent;
}
System.out.println("Answer = " + result);
}
}
Output
Answer = 81
In this program, base and exponent are assigned values 3 and 4 respectively.
Using the while loop, we keep on multiplying the result by base until the exponent becomes zero.
In this case, we multiply result by base 4 times in total, so result = 1 * 3 * 3 * 3 * 3 = 81.
Example 2: Calculate the power of a number using a for loop
class Main {
public static void main(String[] args) {
int base = 3, exponent = 4;
long result = 1;
for (; exponent != 0; --exponent) {
result *= base;
}
System.out.println("Answer = " + result);
}
}
Output
Answer = 81
Here, instead of using a while loop, we've used a for loop.
After each iteration, the exponent is decremented by 1, and the result is multiplied by the base exponent number of times.
Both programs above do not work if you have a negative exponent. For that, you need to use the pow() function in Java standard library.
Example 3: Calculate the power of a number using pow() function
class Main {
public static void main(String[] args) {
int base = 3, exponent = -4;
double result = Math.pow(base, exponent);
System.out.println("Answer = " + result);
}
}
Output
Answer = 0.012345679012345678
In this program, we use Java's Math.pow() function to calculate the power of the given base.
We can also compute the power of a negative number using the pow() method.
Example 4: Compute Power of Negative Number
class Main {
public static void main(String[] args) {
// negative number
int base = -3, exponent = 2;
double result = Math.pow(base, exponent);
System.out.println("Answer = " + result);
}
}
Output
Answer = 9.0
Here, we have used the pow() method to compute the power of a negative number -3.