Four File Handling Hacks which every C/C++ Programmer should know

We will discuss about four file hacks listed as below-

1. Rename – Rename a file using C/C++
2. Remove – Remove a file using C/C++
3. File Size – Get the file size using C/C++
4. Check existence – Check whether a file exists or not in C/C++

C++

// C++ Program to demonstrate the
// four file hacks every C/C++ must know

// Note that we are assuming that the files
// are present in the same file as the program
// before doing the below four hacks

#include <iostream>
#include <stdlib.h>
using namespace std;

// A Function to get the file size
unsigned long long int fileSize(const char *filename)
{
    // Open the file
    FILE *fh = fopen(filename, "rb");
    fseek(fh, 0, SEEK_END);
    unsigned long long int size = ftell(fh);
    fclose(fh);

    return size;
}

// A Function to check if the file exists or not
bool fileExists(const char * fname)
{
    FILE *file;
    if (file = fopen(fname, "r"))
    {
        fclose(file);
        return true;
    }
    return false;
}

// Driver Program to test above functions
int main()
{
    cout << fileSize("Passwords.txt") << " Bytes\n";
    cout << fileSize("Notes.docx") << " Bytes\n";

    if (fileExists("OldData.txt") == true )
        cout << "The File exists\n";
    else
        cout << "The File doesn't exist\n";

    rename("Videos", "English_Videos");
    rename("Songs", "English_Songs");

    remove("OldData.txt");
    remove("Notes.docx");

    if (fileExists("OldData.txt") == true )
        cout << "The File exists\n";
    else
        cout << "The File doesn't exist\n";

    return 0;
}

// This code is contributed by sarajadhav12052009

C

// A C Program to demonstrate the
// four file hacks every C/C++ must know

// Note that we are assuming that the files
// are present in the same file as the program
// before doing the below four hacks
#include<stdio.h>
#include<stdlib.h>
#include<stdbool.h>

// A Function to get the file size
unsigned long long int fileSize(const char *filename)
{
    // Open the file
    FILE *fh = fopen(filename, "rb");
    fseek(fh, 0, SEEK_END);
    unsigned long long int size = ftell(fh);
    fclose(fh);

    return (size);
}

// A Function to check if the file exists or not
bool fileExists(const char * fname)
{
    FILE *file;
    if (file = fopen(fname, "r"))
    {
        fclose(file);
        return (true);
    }
    return (false);
}

// Driver Program to test above functions
int main()
{
    printf("%llu Bytes\n", fileSize("Passwords.txt"));
    printf("%llu Bytes\n", fileSize("Notes.docx"));

    if (fileExists("OldData.txt") == true )
        printf("The File exists\n");
    else
        printf("The File doesn't exist\n");

    rename("Videos", "English_Videos");
    rename("Songs", "English_Songs");

    remove("OldData.txt");
    remove("Notes.docx");

    if (fileExists("OldData.txt") == true )
        printf("The File exists\n");
    else
        printf("The File doesn't exist\n");

    return 0;
}

Output:

Screenshot before executing the program :

Screenshot after executing the program :

This article is contributed by Rachit Belwariar. If you like GeeksforGeeks and would like to contribute, you can also write an article and mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks. 

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