Mastering File Handling in C: Reading and Writing Files

File handling is a crucial aspect of C programming, enabling you to interact with external files for data input and output. In this comprehensive guide, we’ll explore the essentials of file handling in C, focusing on reading and writing files. Real-world examples with outputs will illustrate the concepts and help you become proficient in handling files in C.

Introduction to File Handling

File handling in C involves operations such as opening, reading, writing, and closing files. The standard C library provides functions and techniques to perform these operations.

Reading Files

Example: Reading a Text File

#include <stdio.h>
int main() {
    FILE *file;
    char ch;
    // Open a text file for reading
    file = fopen("sample.txt", "r");
    if (file == NULL) {
        printf("File not found or unable to open.\n");
        return 1;
    }
    // Read and print the contents character by character
    while ((ch = fgetc(file)) != EOF) {
        printf("%c", ch);
    }
    // Close the file
    fclose(file);
    return 0;
}

Hello, World!

#include <stdio.h>
int main() {
    FILE *file;
    // Open a text file for writing
    file = fopen("output.txt", "w");
    if (file == NULL) {
        printf("Unable to create or open the file.\n");
        return 1;
    }
    // Write data to the file
    fprintf(file, "This is a sample text written to a file.\n");
    // Close the file
    fclose(file);
    return 0;
}