C

File Handling in C

C 134 views Dec 22, 2025 2 min read

File handling in C is used to store data permanently on secondary storage (files).
C provides file handling functions through the stdio.h library.

Types of Files

  1. Text Files

  2. Binary Files

File Pointer

  • A file is accessed using a FILE pointer

FILE *fp;

Opening a File

fopen() Function

fp = fopen("filename", "mode");

File Opening Modes

ModeDescription
rRead
wWrite
aAppend
r+Read and write
w+Write and read
a+Append and read

Closing a File

fclose(fp);

Writing to a File

Using fprintf()

fprintf(fp, "Hello C");

Using fputc()

fputc('A', fp);

Reading from a File

Using fscanf()

fscanf(fp, "%s", str);

Using fgetc()

ch = fgetc(fp);

Example Program (Write to File)

#include 

int main() {
    FILE *fp;
    fp = fopen("data.txt", "w");

    if (fp == NULL) {
        printf("File cannot be opened");
        return 0;
    }

    fprintf(fp, "Welcome to C");
    fclose(fp);
    return 0;
}

Example Program (Read from File)

#include 

int main() {
    FILE *fp;
    char ch;

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

    if (fp == NULL) {
        printf("File not found");
        return 0;
    }

    while ((ch = fgetc(fp)) != EOF) {
        printf("%c", ch);
    }

    fclose(fp);
    return 0;
}

feof() Function

Checks end of file.

feof(fp);

Advantages of File Handling

  • Permanent data storage

  • Data sharing between programs

  • Large data handling

Summary

  • File handling uses FILE pointer

  • fopen() opens a file

  • fclose() closes a file

  • Read and write using file functions

  • Supports text and binary files

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