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, Loop, Array

## Logic to find frequency of digits in any number

Before I explain the logic of counting frequency of digits. You must have a good understanding of below three concepts.

- Program to find last digit of a number.
- Program to reverse numbers.
- Program to read and print array elements.

Below is the step by step description to count frequency of digits in an integer.

- Read a number from user. Store it in some variable say num.
- Define an array to hold frequency of size 10 i.e. freq[10]. Now why size 10? Because total number of digits is 10 0, 1, 2, ... , 8, 9.
- Initialize all elements of frequency array with 0 i.e. freq[10] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}. Assuming that the 0th index will hold the frequency of 0. 1st index will hold frequency of 1. So on 9th index of freq will store the frequency of 9.
- Extract the last digit of number by performing modulo division by 10. Store the last digit in some variable say lastDigit = num % 10. The value in lastDigit is always between 0-9 inclusive. This last digit can be used as an index to freq array.
- Remove the last digit of the number. As it is processed and not required further. Last digit is removed by dividing the number by 10 i.e. num = num / 10.
- Increment the frequency value of lastDigit found above. Using freq[lastDigit]++.
- Repeat step 4-6 till number is greater than 0.

## 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 int main() { long long num, n; int i, lastDigit; int freq[BASE]; printf("Enter any number: "); scanf("%lld", &num); // Initialize frequency array with 0 for(i=0; i<BASE; i++) { freq[i] = 0; } n = num; //Copy the value of num to n while(n != 0) { // Get last digit lastDigit = n % 10; // Remove the last digit n /= 10; // Increment the 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; }

**Note:** Do not confuse with the statement n /= 10. It is same as n = n / 10. You can use any of them according to your comfort.

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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