#include<stdbool.h>
#include<stdio.h>

int main(void)
{
 bool digit_seen[10] = {false};
 int digit;
 long n;
 
 printf("Enter a number:");
 scanf("%ld",&n);
 
 while (n > 0){
   
    digit = n % 10;
     if (digit_seen[digit])
      break;
     digit_seen[digit] = true;
      n /= 10;  

}
 if (n > 0)  
   printf("%d\n",digit);



return 0;
   
}
 帮我看看比如输入939577则会输出7.如何才能继续循环直到输出所有的重复数字呢？如7   9   

#include<stdbool.h>
#include<stdio.h>

int main(void)
{
bool digit_seen[10] = {false};
int digit;
long n;

printf("Enter a number:");
scanf("%ld",&n);

while (n > 0){
   
    digit = n % 10;
     if (digit_seen[digit])
     printf("%d\n",digit);//在循环内打印
            // break;为啥要跳出循环
     digit_seen[digit] = true;
      n /= 10;  

}
return 0;
   
}

刚试过了，是可以的。明白