 # C Program to Count Number of Digits in an Integer

To understand this example, you should have the knowledge of the following C programming topics:

This program takes an integer from the user and calculates the number of digits. For example: If the user enters 2319, the output of the program will be 4.

## Program to Count the Number of Digits

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

// iterate at least once, then until n becomes 0
// remove last digit from n in each iteration
// increase count by 1 in each iteration
do {
n /= 10;
++count;
} while (n != 0);

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

Output

```Enter an integer: 3452
Number of digits: 4
```

The integer entered by the user is stored in variable n. Then the `do...while` loop is iterated until the test expression `n! = 0` is evaluated to 0 (false).

• After the first iteration, the value of n will be 345 and the `count` is incremented to 1.
• After the second iteration, the value of n will be 34 and the `count` is incremented to 2.
• After the third iteration, the value of n will be 3 and the `count` is incremented to 3.
• After the fourth iteration, the value of n will be 0 and the `count` is incremented to 4.
• Then the test expression of the loop is evaluated to false and the loop terminates.

Note: We have used a `do...while` loop to ensure that we get the correct digit count when the user enters 0.