C PROGRAMMING PROGRAM • FILE HANDLING

Write to and Read from a Text File

Learn how to write to and read from a text file using a clear C program.

IntermediateFILE pointerfputs()fgets()

PROBLEM UNDERSTANDING

Input and expected output

Sample input

Learning file handling

Sample output

Stored message: Learning file handling

COMPLETE C PROGRAM

Complete C implementation

#include <stdio.h>

int main(void)
{
    char message[300], stored[300];

    printf("Enter a message: ");
    fgets(message, sizeof message, stdin);
    FILE *file = fopen("message.txt", "w");
    if (file == NULL) { perror("message.txt"); return 1; }
    fputs(message, file);
    fclose(file);

    file = fopen("message.txt", "r");
    if (file == NULL) { perror("message.txt"); return 1; }
    if (fgets(stored, sizeof stored, file) != NULL) printf("Stored message: %s", stored);
    fclose(file);
    return 0;
}

CURRENT STEP

Select Start to walk through the important lines.

SELECTED LINE

No line selected

EXPECTED OUTPUT FOR THE SAMPLE

Stored message: Learning file handling

0%Step 0 of 0

PROGRAM EXPLANATION

Algorithm and explanation

Read the required input values.
Open a file in write mode, close it, reopen it in read mode and display the stored line.
Display the computed result.

Open a file in write mode, close it, reopen it in read mode and display the stored line.

EFFICIENCY

Time and space complexity

Time complexity

O(n)

Auxiliary space

O(n)

DEBUGGING CHECKLIST

Common mistakes

Check this

Use the correct format specifier for every variable.

Check this

Initialize variables before using their values.

Check this

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.