C Exercises: Reads an integer and count number of 3s in the given number

Last update on September 18 2025 12:35:04 (UTC/GMT +8 hours)

Count occurrences of the digit 3 in a number

Write a C program that reads an integer (7 digits or fewer) and counts the number of 3s in the given number.

Sample Input: 538453

Sample Solution:

C Code:

#include<stdio.h>

// Function to count the occurrences of digit '3' in a number
int count_three(int);

int main()
{
int num;   
    // Prompt user for input
printf("Input a number: ");
scanf("%d", &num);    
    // Call the function count_three and print the result
printf("The number of threes in the said number is %d\n", count_three(num) );
return 0;
}

int count_three(int num) 
{
int ctr = 0;    // Initialize counter variable
int remainder;  // Variable to store the remainder

    // Loop until num is greater than 0
while(num> 0) {
remainder = num % 10;   // Get the last digit
num /= 10;              // Remove the last digit

if(remainder == 3)      // Check if the last digit is 3
ctr++;              // Increment counter if it is 3
    }

return ctr;                 // Return the count of occurrences of 3
}

Sample Output:

Input a number: The number of threes in the said number is 2.

Pictorial Presentation:

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C program to count the frequency of a specified digit in an integer using a loop.
• Write a C program to count how many times the digit 3 appears in a number using recursion.
• Write a C program to count occurrences of digit 3 and compare it with the count of another digit, such as 7.
• Write a C program to compute the frequency of digit 3 in an integer and output the positions where it occurs.

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