在C中翻转双/浮点符号的最快方法

#include <stdio.h>

void flipSign(float *num) {
    unsigned int mask = 1;
    mask = mask << 31;
    *num = *num & mask;
    *num = -(*num);
}

int main() {
    float num = 123.456;
    flipSign(&num);
    printf("%f\n", num);
    return 0;
}