How is the sqrt function used in C++?

In C++, the sqrt() function is used to calculate the square root of a given number. Its syntax is as follows:

#include<cmath>
...
double sqrt(double x);
float sqrt(float x);
long double sqrt(long double x);

The sqrt() function takes one parameter x, which indicates the number to calculate the square root of. It returns a value of type double, representing the square root of x.

To use this function, you need to include the cmath header file. Here is an example:

#include<iostream>
#include<cmath>

int main() {
   double num = 16.0;
   double result = sqrt(num);
   std::cout << "平方根为: " << result << std::endl;
   return 0;
}

The output is: the square root is 4.0.

Please note that the sqrt() function is a mathematical function, so the result it returns is a floating point number. If an integer result is needed, it can be converted to an integer type.