Dharani Tech Edu Hub

File Operations in C

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Introduction

File handling in C allows us to store data permanently in files instead of temporary memory.

👉 Using file operations, we can:

• Create files
• Read data
• Write data
• Update data

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What is a File?

A file is:
👉 A collection of data stored on a storage device

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Why Use File Operations?

• ✔ Store data permanently
• ✔ Handle large data
• ✔ Data reuse
• ✔ Used in real-world applications

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File Pointer

👉 A file pointer is used to access a file

FILE *fp;

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Opening a File

fp = fopen("file.txt", "mode");

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File Modes Table

Mode	Description
r	Read
w	Write
a	Append
r+	Read & Write

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Writing to a File

#include <stdio.h>

int main() {
    FILE *fp;

    fp = fopen("test.txt", "w");

    fprintf(fp, "Hello File Handling");

    fclose(fp);

    return 0;
}

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Output

👉 Creates file and writes data

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Reading from a File

#include <stdio.h>

int main() {
    FILE *fp;
    char str[50];

    fp = fopen("test.txt", "r");

    fgets(str, sizeof(str), fp);

    printf("%s", str);

    fclose(fp);

    return 0;
}

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Output

Hello File Handling

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Closing a File

fclose(fp);

👉 Always close file after use

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File Functions Table

Function	Purpose
fopen()	Open file
fprintf()	Write to file
fscanf()	Read from file
fclose()	Close file

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Important Notes

• Always check if file opened successfully
• Close file after use
• Use correct file mode

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Common Mistakes

• ❌ Forgetting fclose()
• ❌ Wrong file mode
• ❌ File not found error
• ❌ Not checking NULL pointer

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Pro Tips

• ✔ Always check file pointer
• ✔ Use proper file modes
• ✔ Handle errors properly
• ✔ Practice file programs

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Conclusion

File operations allow storing and managing data permanently. They are essential for real-world applications.

Master file handling to build advanced programs.

👉 This article is part of Dharani Tech Edu Hub — where learning programming is made simple and practical.