scanf()正确写法: scanf("%d %d",&m,&n);
#include <stdio.h>
#include<math.h>
int main()
{
int m, n, r;
scanf("%d %d",&m,&n);
while((r=m%n!=0))
{
m=n;
n=r;
printf("%d",n);
}
return 0;
}
while()后边要有{}把你的循环体括起来