In this example, you will learn to count the number of digits in an integer entered by the user. For example if we input 1234 then program returns 4.

## C Program to Count the Number of Digits Using Loop

```	```
#include <stdio.h>
int main() {
long long n;
int count = 0;
printf("Enter an positive number: ");
scanf("%lld", &n);

//this loop runs till value of n not equal to 0
while (n != 0) {
n /= 10;     // n = n/10
++count;
}

printf("Number of digits: %d", count);
}
```
```

Output :

```	```
Enter an positive number: 12563
Number of digits: 5
```
```

## C Program to Count the Number of Digits Using User Define Function

```	```
#include <stdio.h>

int countDigit(long long n)
{
int count = 0;
while (n != 0)
{
n = n / 10;
++count;
}
return count;
}
int main(void)
{
long long n;
printf("Enter an positive number: ");
scanf("%lld", &n);
printf("Number of digits : %d", countDigit(n));
return 0;
}
```
```

Output :

```	```
Enter an positive number: 12586947
Number of digits : 8
```
```