sqrt,sqrtl,sqrtf

#include 
#include 
using namespace std;

int main() {
    float a = 2.0f;
    double b = 2.0;
    long double c = 2.0;

    cout << sqrtf(a) << endl;   // 用于 float
    cout << sqrt(b) << endl;    // 用于 double
    cout << sqrtl(c) << endl;   // 用于 long double
}