C PROGRAMMING PROGRAM • FILE HANDLING

Write and Read a Structure in a Binary File

Learn how to write and read a structure in a binary file using a clear C program.

AdvancedBinary filefwrite()fread()

PROBLEM UNDERSTANDING

Input and expected output

Sample input

No input required

Sample output

101 Anu 92.5

COMPLETE C PROGRAM

Complete C implementation

#include <stdio.h>

struct Record { int id; char name[20]; double marks; };

int main(void)
{
    struct Record original = {101, "Anu", 92.5};
    struct Record restored = {0};
    FILE *file = fopen("record.bin", "wb");
    if (file == NULL) return 1;
    if (fwrite(&original, sizeof original, 1, file) != 1) { fclose(file); return 1; }
    fclose(file);
    file = fopen("record.bin", "rb");
    if (file == NULL) return 1;
    if (fread(&restored, sizeof restored, 1, file) != 1) { fclose(file); return 1; }
    fclose(file);
    printf("%d %s %.1f\n", restored.id, restored.name, restored.marks);
    return 0;
}

CURRENT STEP

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SELECTED LINE

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EXPECTED OUTPUT FOR THE SAMPLE

101 Anu 92.5

0%Step 0 of 0

PROGRAM EXPLANATION

Algorithm and explanation

Read the required input values.
Write the structure bytes as one record and restore the same record with fread.
Display the computed result.

Write the structure bytes as one record and restore the same record with fread.

EFFICIENCY

Time and space complexity

Time complexity

O(1)

Auxiliary space

O(1)

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.