How am I incorrectly using the round() function in C?

Question

I\'m getting unexpected results from the round() and roundf() functions in the math.h library. Here is the sample code:

#         


        

Answer 1

litb was on the right track. -std=c99 didn't work but adding #define _ISOC99_SOURCE worked. So the code looks like:

#define _ISOC99_SOURCE
#include 
#include 

int main(void)
{
...