`luc086.c`¶

Problem Statement

Write a program to copy contents of one file to another. While doing so replace all lowercase characters to their equivalent uppercase characters.

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

This concept detection system is still in beta and may occasionally show incorrect or incomplete results.

Recursion
Pointers
Iteration

Actions¶

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Source Code¶

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

void create_source_file();

int main()
{
    FILE *fs, *ft;
    char ch;

    create_source_file(); // Helper to make code runnable

    fs = fopen("source.txt", "r");
    if (fs == NULL)
    {
        printf("Cannot open source file.\n");
        exit(1);
    }

    ft = fopen("target.txt", "w");
    if (ft == NULL)
    {
        printf("Cannot open target file.\n");
        fclose(fs);
        exit(2);
    }

    while ((ch = fgetc(fs)) != EOF)
    {
        ch = toupper(ch);
        fputc(ch, ft);
    }

    printf("File copied successfully with uppercase conversion.\n");
    printf("Check 'target.txt' for results.\n");

    fclose(fs);
    fclose(ft);

    return 0;
}

void create_source_file()
{
    FILE *fp = fopen("source.txt", "w");
    if (fp)
    {
        fprintf(fp, "This is a sample text.\nIt contains Lowercase letters.\n");
        fclose(fp);
    }
}

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 (luc086.c):

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

    void create_source_file();

    int main()
    {
        FILE *fs, *ft;
        char ch;

        create_source_file(); // Helper to make code runnable

        fs = fopen("source.txt", "r");
        if (fs == NULL)
        {
            printf("Cannot open source file.\n");
            exit(1);
        }

        ft = fopen("target.txt", "w");
        if (ft == NULL)
        {
            printf("Cannot open target file.\n");
            fclose(fs);
            exit(2);
        }

        while ((ch = fgetc(fs)) != EOF)
        {
            ch = toupper(ch);
            fputc(ch, ft);
        }

        printf("File copied successfully with uppercase conversion.\n");
        printf("Check 'target.txt' for results.\n");

        fclose(fs);
        fclose(ft);

        return 0;
    }

    void create_source_file()
    {
        FILE *fp = fopen("source.txt", "w");
        if (fp)
        {
            fprintf(fp, "This is a sample text.\nIt contains Lowercase letters.\n");
            fclose(fp);
        }
    }

luc086.c¶