`luc077.c`¶

Problem Statement

Write a program that receives an integer (less than or equal to nine digits in length) and prints out the number in words.

Metadata¶

Property	Detail
Author	Amit Dutta amitdutta4255@gmail.com
Date	08 Feb 2026
License	MIT License (See the LICENSE file for details)
Difficulty	Beginner (index: 2 / 10)

Concepts¶

Beta Feature

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Pointers
Recursion
Array

Actions¶

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Source Code¶

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>

void convert(long, char *);

char *one[] = {
    "", "One ", "Two ", "Three ", "Four ", "Five ", "Six ", "Seven ", "Eight ", "Nine ", 
    "Ten ", "Eleven ", "Twelve ", "Thirteen ", "Fourteen ", "Fifteen ", "Sixteen ", 
    "Seventeen ", "Eighteen ", "Nineteen "
};

char *ten[] = {
    "", "", "Twenty ", "Thirty ", "Forty ", "Fifty ", "Sixty ", "Seventy ", "Eighty ", "Ninety "
};

int main()
{
    long num;

    printf("Enter a number (max 9 digits): ");
    scanf("%ld", &num);

    if (num <= 0)
    {
        printf("Zero\n");
    }
    else
    {
        printf("In words: ");
        // Indian System: Crore, Lakh, Thousand, Hundred
        convert((num / 10000000), "Crore ");
        convert(((num / 100000) % 100), "Lakh ");
        convert(((num / 1000) % 100), "Thousand ");
        convert(((num / 100) % 10), "Hundred ");
        convert((num % 100), "");
        printf("\n");
    }

    return 0;
}

void convert(long n, char *suffix)
{
    if (n > 19)
    {
        printf("%s%s", ten[n / 10], one[n % 10]);
    }
    else
    {
        printf("%s", one[n]);
    }

    if (n > 0)
    {
        printf("%s", suffix);
    }
}

Explanation¶

Explain with AI

Copy the prompt below and paste it into any AI assistant.

    You are explaining a C programming code to a beginner.

    STRICT RULES:

    - Only use the given code. Do NOT assume anything not present.

    - Do NOT add extra examples.

    - Keep explanation clear and short.

    - If something is unclear, say "Not clear from code".

    - Follow the exact format below. Do NOT change headings.

    FORMAT:

    [START]

    ## What it does

    (Explain the overall purpose in 1-2 sentences)

    ## Step-by-step

    (Explain how the code works in steps, simple language)

    ## Key Concepts

    (List concepts like loop, condition, function, etc.)

    ## Notes

    (Mention any limitations, errors, or assumptions)

    [END]

    CODE (luc077.c):

    #include <stdio.h>
    #include <string.h>
    #include <stdlib.h>
    #include <ctype.h>

    void convert(long, char *);

    char *one[] = {
        "", "One ", "Two ", "Three ", "Four ", "Five ", "Six ", "Seven ", "Eight ", "Nine ", 
        "Ten ", "Eleven ", "Twelve ", "Thirteen ", "Fourteen ", "Fifteen ", "Sixteen ", 
        "Seventeen ", "Eighteen ", "Nineteen "
    };

    char *ten[] = {
        "", "", "Twenty ", "Thirty ", "Forty ", "Fifty ", "Sixty ", "Seventy ", "Eighty ", "Ninety "
    };

    int main()
    {
        long num;

        printf("Enter a number (max 9 digits): ");
        scanf("%ld", &num);

        if (num <= 0)
        {
            printf("Zero\n");
        }
        else
        {
            printf("In words: ");
            // Indian System: Crore, Lakh, Thousand, Hundred
            convert((num / 10000000), "Crore ");
            convert(((num / 100000) % 100), "Lakh ");
            convert(((num / 1000) % 100), "Thousand ");
            convert(((num / 100) % 10), "Hundred ");
            convert((num % 100), "");
            printf("\n");
        }

        return 0;
    }

    void convert(long n, char *suffix)
    {
        if (n > 19)
        {
            printf("%s%s", ten[n / 10], one[n % 10]);
        }
        else
        {
            printf("%s", one[n]);
        }

        if (n > 0)
        {
            printf("%s", suffix);
        }
    }

luc077.c¶