#include <stdio.h>
void main()
{
  int m,n,t1;
  int gcd(int x,int y);
  printf("input two integer numbers:\n");
  scanf("%d,%d",&a,&b);
  t1=gcd(m,n)；
  printf("The highest common divisor is %d\n",t1);
  printf("The lowest common multiple is %d\n",m*n/t1);
}

int gcd(int x,int y)
{
   if(x%y==0)
    return y;
   else
    return gcd(y,x%y);
}


其中在定义gcd时，为什么不用比较x y大小，就直接用if语句了？？