Write a C program to count frequency of digits in a given number. How to find frequency of digits in a given number using loop in C programming. Logic to find total occurrences of each digits in a given number in C program.

**Example**

**Input**

Input any number: 116540

**Output**

Frequency of 0 = 1 Frequency of 1 = 2 Frequency of 2 = 0 Frequency of 3 = 0 Frequency of 4 = 1 Frequency of 5 = 1 Frequency of 6 = 1 Frequency of 7 = 0 Frequency of 8 = 0 Frequency of 9 = 0

## Required knowledge

Basic C programming, For loop, While loop, Array

## Logic to find frequency of digits in a number

Step by step description to count frequency of digits in a number.

- Input a number from user. Store it in some variable say
`num`. - Declare and initialize an array of size 10 to store frequency of each digit. Why declare array of size 10? Because total number of digits is 10 i.e.
`0, 1, 2, 3, 4, 5, 6, 7, 8, 9`. - Extract last digit of given number by performing modulo division by 10. Store the result in some variable say
`lastDigit = num % 10`

. - Increment the frequency of a digit found above i.e.
`lastDigit`. To increment frequency perform`freq[lastDigit]++`

.The value of

`lastDigit`will be always between`0-9`inclusive. Hence it can be used as an index to`freq`array. - Remove last digit from the number since it is processed and not required further. To remove last digit divide the number by 10 i.e.
`num = num / 10`

. - Repeat step 3 to 5 till number is greater than 0.
- Finally print frequency of each element in the
`freq`array.

## Program to count frequency of digits in a number

```
/**
* C program to count frequency of digits in a given number
*/
#include <stdio.h>
#define BASE 10 /* Constant */
int main()
{
long long num, n;
int i, lastDigit;
int freq[BASE];
/* Input number from user */
printf("Enter any number: ");
scanf("%lld", &num);
/* Initialize frequency array with 0 */
for(i=0; i<BASE; i++)
{
freq[i] = 0;
}
/* Copy the value of 'num' to 'n' */
n = num;
/* Run till 'n' is not equal to zero */
while(n != 0)
{
/* Get last digit */
lastDigit = n % 10;
/* Remove last digit */
n /= 10;
/* Increment frequency array */
freq[lastDigit]++;
}
/* Print frequency of each digit */
printf("Frequency of each digit in %lld is: \n", num);
for(i=0; i<BASE; i++)
{
printf("Frequency of %d = %d\n", i, freq[i]);
}
return 0;
}
```

Let us take a note on above program.

`#define BASE 10`

defines a constant with name`BASE`. Since there are 10 digits in decimal number system hence I have defined it as a constant variable.- I have declared
`num`with`long long`

data type and to access a`long long`

I have used`%lld`

format specifier.However some compiler does not support

`long long`

type. If you are facing issues with`long long`

type you can use`long`

or`int`

type. - In statement
`n /= 10;`

I have used shorthand assignment operator which is equivalent to`n = n / 10;`

. - The increment statement
`freq[lastDigit]++;`

is equivalent to`freq[lastDigit] = freq[lastDigit] + 1;`

.

Output

Enter any number: 11203458760011 Frequency of each digit in 11203458760011 is: Frequency of 0 = 3 Frequency of 1 = 4 Frequency of 2 = 1 Frequency of 3 = 1 Frequency of 4 = 1 Frequency of 5 = 1 Frequency of 6 = 1 Frequency of 7 = 1 Frequency of 8 = 1 Frequency of 9 = 0

Happy coding 😉

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