求大佬解释

# include <stdio.h>
int main ( )
{
   int l=0, r=0, js=0, tem=0;
   scanf ("%d%d",&l,&r);
   for (int i=l; i<=r; i++){
     tem = i;
     while (tem){
   if ((tem%10)==2){
      js++;
      }
     /*为什么
       if ((tem%10)==2)就可以过
       而if ((tem%10)==l)就不行呢
       我认为用l更加合理啊＞﹏＜*/
	tem /= 10;
	}
   }
  printf ("%d",js);
	
  return 0;
}