# C Program to Count Number of Digits in an Integer

• Write a C program to count digits of a number.

Given an integer N, we have to count the number of digits of N and print it on screen.

##### For Example
Number of digits in 423536 is 6.

## C program to count the number of digits in a number using loop

In this program, we first take a number as input from user using scanf function. Then inside while loop, we keep on removing right most digit(Least significant digit) of number and increment a counter(count variable) till number becomes zero. Finally, we print the value of count variable on screen.

```/*
*  C program to count tne number of digits in an integer
*/
#include<stdio.h>
#include<conio.h>

int main() {
int num, temp, count=0;
printf("Enter an integer\n");
scanf("%d", &num);
temp = num;

while(temp!=0) {
temp = temp/10;
++count;
}
printf("Number of digits in %d : %d",num, count);

getch();
return 0;
}
```
Program Output
```Enter an integer
12345
Number of digits in 12345 : 5
```
```Enter an integer
-345
Number of digits in -345 : 3
```

## C program to count the number of digits in a number using logarithm

We can use log10(logarithm of base 10) to count the number of digits of positive numbers (logarithm is not defined for negative numbers).
Digit count of N = log10(N) + 1

```/*
*  C program to count the number of digits in an integer using logarithm
*/
#include<stdio.h>
#include<conio.h>
#include<math.h>

int main() {
int num, temp;
printf("Enter an integer\n");
scanf("%d", &num);
temp = num;

/*If input number is negativ ethen make it positive */
if(temp < 0)
temp = temp*-1;

if(temp) {
/* If input number is non-zero */
printf("Number of digits in %d : %d",num, (int)log10(temp)+1);
} else {
printf("Number of digits in %d : %d",num, 1);
}

getch();
return 0;
}
```
Program Output
```Enter an integer
6534
Number of digits in 6534 : 4
```
```Enter an integer
-423
Number of digits in -423 : 3
```

Related Topics
 C program to find product of digits of a number using while loop C program to find sum of least and most significant digits of a number C program to add digits of a number C program to reverse a number using recursion C program to find sum of digits of a number using recursion C program to make a simple calculator using switch statement C program to convert string to integer C program to calculate power of a number C program to find gcd of two numbers List of all C programs