How can I do it - with pointer and only one loop ?

for exmpl function - unsigned int dif(const char *str)

```
counter = 0;
for(i = 0; i < N; i++)
A[i] = 0;
do
{
A[tmp % 10]++;
tmp /= 10;
}
while(tmp);
for(i = 0; i < N; i++)
if(A[i])counter++;
printf("\n\nThere r %u different digits in the number %u\n",counter , n);
```