File Handling in C: Reading, Writing, and Manipulating Files with Examples

File Handling in C
File handling in C allows programs to read from and write to files on disk. Files are
an essential part of most applications, as they enable data to persist beyond the
execution of a program. In C, the stdio.h library provides functions to perform file
operations like opening, reading, writing, and closing files.

1. Types of Files in C
In C, files can be categorized into two main types:

 Text files: These contain plain text data, where each character is stored as a
sequence of bytes.
 Binary files: These contain data in a format that is not human-readable,
such as images or executable files, and the data is stored as raw binary.



2. File Operations in C
C provides several functions for performing file operations. These include:

 Opening a file
 Reading from a file
 Writing to a file
 Closing a file



3. Opening a File
The fopen() function is used to open a file in C. It takes two arguments: the name
of the file and the mode in which the file should be opened. If the file is
successfully opened, fopen() returns a pointer to the file; otherwise, it returns
NULL.

, File Opening Modes:

 "r": Open a file for reading.
 "w": Open a file for writing (if the file exists, it is truncated).
 "a": Open a file for appending (writing at the end of the file).
 "r+": Open a file for reading and writing.
 "w+": Open a file for reading and writing (if the file exists, it is truncated).
 "a+": Open a file for reading and appending.

Example of opening a file:

#include <stdio.h>

int main() {
FILE *file = fopen("example.txt", "r");

if (file == NULL) {
printf("Error opening file.\n");
return 1;
}

// Perform file operations

fclose(file); // Close the file
return 0;
}


4. Reading from a File
You can read data from a file using functions like fgetc(), fgets(), or fread().

 fgetc(): Reads a single character from a file.
 fgets(): Reads a line of text from a file.
 fread(): Reads binary data from a file.