How do I take out the sign?

(x > 0) - (x < 0)

//If you unscramble the code above,
if (x > 0) return 1;
if (x < 0) return -1;
return 0;

template <typename T> int sgn(T val) {
    return (T(0) < val) - (val < T(0));
}

//< If you don't want to see GCC issuing -Wtype-limits warning because of 0, write the following code together (select)

template <typename T> inline constexpr
int signum(T x, std::false_type is_signed) {
    return T(0) < x;
}

template <typename T> inline constexpr
int signum(T x, std::true_type is_signed) {
    return (T(0) < x) - (x < T(0));
}

template <typename T> inline constexpr
int signum(T x) {
    return signum(x, std::is_signed<T>());
}

#include <math.h> //C
#include <cmath> //C++11
...
float a = 1.0;
result1 = copysign(1.0, a); //1.0
result2 = copysign(10.0, a); //10.0

int main(){
    float fl1 = (0.0);
    float fl2 = (+0.0);
    float fl3 = (-0.0);
    cout << copysign(1.0, fl1) << endl; //1.0
    cout << copysign(1.0, fl2) << endl; //1.0
    cout << copysign(1.0, fl3) << endl; //-1.0
}