Overwrite an existing text file c++

Question

This is how my Save As works - it is copying the current file's lines until it reaches the first figure and then I use my print methods to print the figure's info and then close the tag. ``` std::ofstream newFile(filePath1_fixed, std::ios::app); std::fstream openedFile(filePath); std::string line1; while (std::getline(openedFile, line1)) { if (line1.find(" "; ``` My question is how to save the changes to the current file? I tried something like this: ``` std::ifstream openedFile(filePath); std::ofstream newFile(filePath, std::ios::app); std::string line1; std::string info_beg[100]; int t = 0; while (std::getline(openedFile, line1)) { std::cout << "HELLYEAH"; if (line1.find("

Accepted Answer

Use `ios::trunc` instead of `ios::app`

Using `std::ios::app` in the constructor for your `std::ofstream` tells the program to append to the file and not overwrite it. If you want to overwrite it (ie truncate), then using `std::ios::trunc` will tell the program to overwrite the existing file. `ofstream` does this by default, so you could just write the initialization as just `std::ofstream newFile(filePath);`.

Also, don't try to read the file and write to it at the same time; that won't work. Use `ifstream` to get the data into the buffer, then use `close()` to close the file. Then initialize newFile to overwrite the file and write out the buffer.

Overwrite an existing text file c++

Solution

Problem