C/C++自己实现remainder函数

#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
using namespace std;
//VS2010不提供remainder这个函数,自己实现
//http://www.cplusplus.com/reference/cmath/remainder/
//Returns the floating - point remainder of numer / denom(rounded to nearest) :
//remainder = numer - rquot * denom
//Where rquot is the result of : numer / denom, rounded toward the nearest integral value(with halfway cases rounded toward the even number).
//A similar function, fmod, returns the same but with the quotient truncated(rounded towards zero) instead.
#define ROUND(d)  int(d + 0.5)//四舍五入
double remainder(double numer, double denom)
{
  int rquot = ROUND(numer / denom);//remainder和fmod的区别就是要不要四舍五入
  double remainder = numer - rquot * denom;
  return remainder;
}
int main()
{
  double da1 = fabs(fmod(5.f, 2.55f));
  double da2 = fabs(remainder(5.f, 2.55f));
  std::cout << "Hello World!\n" << da1  << "," << da2;
}