强制输入大于或等于 0 且小于 24

Question

#include<stdio.h>

int main ()
{
int n,a=0,b=24;
do
  {
    scanf("%d",n); //ask the user to enter a value of n less than 24 
                  // but greater than 0. 
  } while(/*boolean expression logic*/)

if(a<n<b)
    {
    printf("%d\n",n);
    }
    return 0;
}

我要评价：

If the value of n is greater than or equal to 0 and less than 24 (less than or equal to 23) then

.... go to the if statement and print the value of n

otherwise

... ask the user to input the value of n i.e. it should again go back in the loop.

Answer 1

您希望程序一直询问值直到 n>=0 && n<24；换句话说，你想在 !(n>=0 && n<24) 时继续求值，使用 De Morgan's law 我们可以写成 !(n>=0) || !(n<24)，可以简化为 n<0 || n>=24

do
{
    scanf("%d",n);
}
while(n<0 || n>=24)

强制输入大于或等于 0 且小于 24

Enforce input greater than or equal to 0 and less than 24

c

boolean-expression

do-while