deleting stuff from files

[randomFIRE]

How can I delete part of the text inside a file? I've navigated to the place where I need to delete using seekg, and now I can't think of how to actually get rid of that part of the document.

[v0id]

Usually when doing this, you don't do it directly to the file.

First you are going to save the content of the file, using a input stream pointer (std:: ifstream), then manipulate with the content, and then use a output stream pointer (std:: ofstream) to write to the file again (use std::ios::trunc to overwrite file).

This shows how to open, read, manipulate and then write to the file again:

#include <iostream>
#include <fstream>
#include <string>

#define FILENAME "test_file.txt"

int main()
{
	std::string   fileContent;
	std::string   fileContentTemporary;
	std::ofstream outputFile;
	std::ifstream inputFile;
	
	// Open the file, and read the content
	inputFile.open(FILENAME, std::ios::in);
	if(inputFile.is_open())
	{
		while(getline(inputFile, fileContentTemporary))
			fileContent += fileContentTemporary;
		inputFile.close();
	}
	
	// Manipulate with the file content
	fileContent += " -- this was appended to the file";
	// ...
	
	// Open the file, and write the manipulated content
	outputFile.open(FILENAME, std::ios::out | std::ios::trunc);
	if(outputFile.is_open())
	{
		outputFile << fileContent;
		outputFile.close();
	}
	
	return 0;
}

A better way would maybe be, instead of having to stream pointers (I/O), then only have one - the multi-streamed one (std::fstream). This was just to show how to use both types of the stream pointers. If you want to use std::fstream, then you have to use it in the same way, just remember to set the right I/O-flags each time. After you've set the flags once, using the constructor, you can always use the member, std::fstream::flags().