[SOLVED] sqrtf function alternative in Visual Studio

Issue

I am writing a project in Visual Studio then I use GCC in order to compile it. Sometimes it causes some problems: This time I cannot use sqrtf function because VS accepts it however GCC does not. So I need to find some way (maybe mathematical approach to calculate square root) to find square root of some number in a way both GCC and VS will accept. To be more precise this is the line which causes a problem:

float x_f = circleRadius - sqrtf((float)((circleRadius * circleRadius) - (y * y)));

I need to find the square root of (circleRadius^2 - y^2)

Solution

std::sqrt solves this problem:

#include <cmath>

auto foo(int circleRadius, int y) {
    float x_f = circleRadius - std::sqrt((float)(circleRadius * circleRadius - y * y));
}

compiles for both msvc and gcc according to https://godbolt.org/z/g9MJH6

You should prefer std::sqrt to sqrtf in C++. It works with more types, i.e., you could write your function more generically. It also does not use hungarian notation.

Edit: If you do not care if the calculation returns a float or a double, you could omit the cast and write the following:

auto x_f = circleRadius - std::sqrt(circleRadius * circleRadius - y * y);

If you care that a float is used, you can use std::sqrtf instead. If you have to use a cast, you should generally prefer static_cast to C-style casts. Reasons for this are listed here.

Answered By - Stefan Groth