为什么我的while循环不会在此C代码中启动？

Question

I'm new at programming in c but I just don't understand why this code won't run properly after compiling. For now, I just want it to take numbers between 10 and 100 without errors. Then later I'll add return 1 for errors and 0 for success.

#include <stdio.h>
#include <stdlib.h>

int intGet(int, int);
int error();

int main(void)
{
    int Min, Max, UserIn;
    Min = 10;
    Max = 100;

    printf("Enter a number in between [10 -­100]: \n");
    scanf("%d", &UserIn);
    printf("Read %d\n", UserIn);

    while (UserIn < Min && UserIn > Max)
    {
        printf("Invalid \n");
        scanf("%d", &UserIn);
    }
    /* What I did to fix
      while ((UserIn > Min) || (UserIn < Max)){
         printf("Enter a number in between [10 -­100]: \n");
         scanf("%d",&UserIn);       
         printf("Read %d\n",UserIn);

       while ((UserIn < Min) || (UserIn > Max)){
         printf("Invalid \n");
         scanf("%d", &UserIn);
          printf("Read %d\n", UserIn);


       }
      }*/

    return EXIT_SUCCESS;
}

int intGet(int min, int max)
{

}

int error()
{

}

Answer 1

while (UserIn < Min && UserIn > Max)

userIn can never meet both conditions. Change it to:

whihe (userIn < Min || userIn > Max)

Answer 2

You do realise that scanf does return a value? See http://linux.die.net/man/3/scanf

If it does not return 1 then you need to "eat" some input.

Better to read in a string and parse that.

Also

while (UserIn < Min && UserIn > Max)

should be

while (UserIn < Min || UserIn > Max)

Answer 3

replace

while (UserIn<Min && UserIn>Max){

with:

while (UserIn<Min || UserIn>Max){

also you can replace your while loop with do ... while. then you will not have double scanf

Answer 4

To help you debug this, try this code:

while ((UserIn < Min) || (UserIn > Max))
{
    printf("Invalid \n");
    scanf("%d", &UserIn);
    printf("Read %d\n", UserIn);
}

Also, this while loop will only run if the first inputted value for Userin was < 10 or > 100.