&&条件作为|| 在c中执行while循环

Question

The AND ( && ) condition evaluates as OR ( || ) in this code. For ex., when user inputs numbers 6 and 7 , the output is 12 but when the I replace && with || the output is 42 .

#include<stdio.h>

int main()
{
    int a,b,max,lcm;

    printf("Enter 2 numbers: ");
    scanf("%d %d", &a, &b);

    if(a>b)
    {
        max=a;
    }
    else
    {
        max=b;  
    }

    do
    {
        max++;
    } while(max%a!=0 && max%b!=0);

    lcm=max;
    printf("LCM of %d and %d is %d\n", a,b,lcm);

    return 0;
}

Answer 1

No, the && condition is working as an and condition, just as it should. When you input 6 and 7 , max%a evaluates to 0 when max is 12 . At that point max%a != 0 evaluates to false ( false && true == false ), and max%a != 0 && max%b != 0 evaluates to false , and your loop exits. However, max%a != 0 || max%b != 0 max%a != 0 || max%b != 0 evaluates to true ( max%b is 5 for a max of 12 and b of 7 , false || true == true ), so the loop continues.

Answer 2

I would change the do {..} while (...); loop to:

while (1)
{
   max++;
   if ( max%a == 0 && max%b == 0 )
   {
      break;
   }
} 

It is so much easier to follow, at least for me.