#include<stdio.h>
int main()
{
    int x,y,i;
    scanf("%d",&x);
    if(x>10000||x<1)
   
        printf("please input 4 wei shu");
        else
        {    while(x!=0)
            {
               i=0;
                y=x%10;
                i=i+1;
                printf("%d,",y);
                x=x/10;
               
            }
        }
            printf("you input a%dwei shu\n",i);
   
    return 0;
}
我想表达每循环一次.i都累加1，以达到计算位数的目的.
可是每次i的结果都是1;

int main()
{
    int x,y,i;
    i=0;
    scanf("%d", &x);
    if (x > 10000 || x < 1)
        printf("please input 4 wei shu");
    else
    {   
        while (x != 0)
        {
            y=x%10;
            i=i+1;
            printf("%d,",y);
            x=x/10;
               
        }
    }
    printf("you input a %d wei shu\n",i);   
    return 0;
}

#include<stdio.h>
int main()
{
    int x,y,i=0;
    scanf("%d",&x);
    if(x>10000||x<1)
   
        printf("please input 4 wei shu");
        else
        {    while(x!=0)
            
            {
                y=x%10;
                i=i+1;
                printf("%d,",y);
                x=x/10;
               
            }
        }
            printf("you input a%dwei shu\n",i);
   
    return 0;
}
改一点就行了,因为你的i=0;在i=i+1;前面,而且在while里,所以不行.应该把i=0放while外面.

你的i=0不应该放在循环内，否则每次循环都会把i赋值为0