What is the usage of the pow function in C++?

In C++, the `pow()` function is used to calculate an exponent of a number. Here is how it is used:

#include <cmath>
double pow(double base, double exponent);

Base: The number being calculated.

exponent: the power to which a number is raised to.

This function returns the result of raising `base` to the power of `exponent`. It is important to note that the parameters and return value of the `pow()` function are both of type `double`, so it can handle floating-point numbers.

Here are some examples:

#include <iostream>
#include <cmath>
int main() {
    double result;
    // 计算3的4次方
    result = pow(3, 4);
    std::cout << "3^4 = " << result << std::endl;
    // 计算2的平方根
    result = pow(2, 0.5);
    std::cout << "Square root of 2: " << result << std::endl;
    return 0;
}

Output:

3^4 = 81
Square root of 2: 1.41421

Please note that the `pow()` function returns a floating point number of type `double`, if you need to convert it to an integer, you can use type casting or other methods to do so.