Extract to file duplicate information

Question

I want to create the file with particular name. If it already exists then I want to create another file with the name appended by some number. For example, I want to create the file log.txt but it is already there. Then I will create new file log1.txt, log2.txt, log3.txt....

Is there any good way to record into the file duplication information?

Answer 1

Just check if the file exists, if yes, check for the next and so on, like in this code:

#include <sys/stat.h>
#include <iostream>
#include <fstream>
#include <string>

/**
 * Check if a file exists
 * @return true if and only if the file exists, false else
 */
bool fileExists(const std::string& file) {
    struct stat buf;
    return (stat(file.c_str(), &buf) == 0);
}

int main() {
        // Base name for our file
        std::string filename = "log.txt";
        // If the file exists...                   
        if(fileExists(filename)) {
                int i = 1;
                // construct the next filename
                filename = "log" + std::to_string(i) + ".txt";
                // and check again,
                // until you find a filename that doesn't exist
                while (fileExists(filename)) {
                        filename = "log" + std::to_string(++i) + ".txt";
                }
        }
        // 'filename' now holds a name for a file that
        // does not exist

        // open the file
        std::ofstream outfile(filename);
        // write 'foo' inside the file
        outfile << "foo\n";
        // close the file
        outfile.close();

        return 0;
}

which will find a non-taken name and create a file with that name, write 'foo' into it and then will close the file, eventually.

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I was inspired for the code from here.