如何在C语言中进行四舍五入？

double round(double x);

#include <stdio.h>
#include <math.h>

int main() {
   double num = 3.6;
   int rounded = round(num);
   
   printf("四舍五入后的值为：%d\n", rounded);
   
   return 0;
}

四舍五入后的值为：4

#include <stdio.h>

int main() {
   int num = 36;
   int rounded = (num + 5) / 10 * 10;
   
   printf("四舍五入后的值为：%d\n", rounded);
   
   return 0;
}

四舍五入后的值为：40