Hidden features of C

Answer 1

the (hidden) feature that "shocked" me when I first saw is about printf. this feature allows you to use variables for formatting format specifiers themselves. look for the code, you will see better:

#include 

int main() {
    int a = 3;
    float b = 6.412355;
    printf("%.*f\n",a,b);
    return 0;
}

the * character achieves this effect.