C PROGRAMMING PROGRAM • LOOPS & NUMBER PROBLEMS

Count Digits in an Integer

Learn how to count digits in an integer using a clear C program.

Beginnerwhile loopInteger divisionDigits

PROBLEM UNDERSTANDING

Input and expected output

Sample input

-90872

Sample output

Digit count = 5

COMPLETE C PROGRAM

Complete C implementation

#include <stdio.h>

int main(void)
{
    long long number, value;
    int count = 0;

    printf("Enter an integer: ");
    scanf("%lld", &number);
    value = number < 0 ? -number : number;
    do {
        count++;
        value /= 10;
    } while (value != 0);
    printf("Digit count = %d\n", count);
    return 0;
}

CURRENT STEP

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SELECTED LINE

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EXPECTED OUTPUT FOR THE SAMPLE

Digit count = 5

0%Step 0 of 0

PROGRAM EXPLANATION

Algorithm and explanation

Read the required input values.
Repeatedly divide the absolute value by 10; a do-while correctly counts zero as one digit.
Display the computed result.

Repeatedly divide the absolute value by 10; a do-while correctly counts zero as one digit.

EFFICIENCY

Time and space complexity

Time complexity

O(d)

Auxiliary space

O(1)

DEBUGGING CHECKLIST

Common mistakes

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Use the correct format specifier for every variable.

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Initialize variables before using their values.

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Check braces, semicolons and input order carefully.

Try it yourself

Practice: Run the program with the sample input, predict its output, and then test one boundary case of your own.