std::fstream / std::filesystem create file with duplicate number

Question

I want to create a file with a number at the end of the file : filename ( number goes here ).txt. The number will tell me if there were duplicates of the file in the directory the file was created : filename.txt .

Example : helloworld (1).txt

Windows also has this functionality when trying to create a file duplicate. Is there way I could do this in C++ 17 ?

I could , but finding functions that are already made is better. — ibrahim muhmud usmani, Mar 29 '22 at 08:03
And perhaps all you need is [a good reference](https://en.cppreference.com/w/cpp) or [some good books](https://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list/388282#388282)? — Some programmer dude, Mar 29 '22 at 08:05

score 2 · Accepted Answer · answered Mar 29 '22 at 09:12

Since no one is giving me any answers, I decided to spend some time on this function that does what I want , and answer my own question , its in C++ 17 for anyone who thinks this is useful :

#include <filesystem>
#include <regex>
#include <fstream>
#include <string>

namespace fs = std::filesystem;

// Just file "std::ostream::open()" except it handles duplicates too
    void create_file_dup(std::string path)
    {
        // Check if file doesnt have duplicates
        if (!fs::exists(path)) {
            std::ofstream(path);
            return;
        }

        // Get filename without path
        std::string filename = (fs::path(path).filename()).string();

        // Since its already a duplicate add "(1)" inbetween the basename and extension
        filename = (fs::path(filename).stem()).string() + " (1)" + (fs::path(filename).extension()).string();

        // Get file's parent directory
        std::string parent = (fs::path(path).parent_path()).string();


        // Loops to check for more duplicates
        for (int dup_count = 2;!fs::exists(parent + filename);dup_count++) {

            std::string dup_c = "(" + std::to_string(dup_count);      // old number
            dup_c + ")";

            std::string dup_cn = "(" + std::to_string(dup_count + 1);   // new number 
            dup_cn + ")";

            filename = std::regex_replace(filename, std::regex(dup_c), dup_cn); // increments : '(1)' -> '(2)'
        }

        // We have found the how many duplicates there are , so create the file with the duplicate number
        std::ofstream(parent + filename);
        return;
    }

std::fstream / std::filesystem create file with duplicate number

1 Answers1