String - Find and erase between two points?

[Jclow]

Hi Guys,

I'm trying to clean up an xml file that has unnecessary elements in it using CPP.
e.g from the following line..

<xd ref="hgfhgfhj" invisible="true" name="bob" age="45" species="vlergan" />

The contents between the quotes can vary, so the idea would be to remove, for example,ref="hgfhgfhj". Given that the contents of the quotes will vary, there is no simple find string and erase that can be used. It looks like I need to..

Search for ref=", get the start position, get the end position, start a search for " at the previous search results end position, then erase between those two points.

The problem I have is that .erase doesn't use start and end positions, only a start position, and length. mainStr.erase(pos, toErase.length());

My original workaround for this was to find the next " and set position in pos2, then just do an int eraselength = pos2-pos; to get a length.
mainStr.erase(pos, eraselength); but .erase doesn't accept an integer for the length.

If any folks out there could give me a tip on this i'd be very grateful as there don't seem to be any examples out there that I can find that relate to this kind of erase use. Thanks

  #include "pch.h"
#pragma once

#include <iostream>
#include <fstream>
#include <string>
#include <algorithm>
#include <functional>
#include <stdio.h>
#include <vector>

void eraseAllSubStr(std::string & mainStr, const std::string & toErase);

int main()

{
	std::string STRING;
	std::ifstream infile;
	infile.open("C:\\test\\myxml.xml");
	while (!infile.eof()) // To get you all the lines.
	{
		getline(infile, STRING); // Saves the line in STRING.
		eraseAllSubStr(STRING,  "visible=\"");
		//eraseSubStringsPre(STRING, { "visible=\"true\"","version=\"1\"","version=\"2\"","version=\"3\"","version=\"4\"" });

		std::cout << STRING <<"\n"; // Prints our STRING.
	}
	infile.close();
	system("pause");

	return 0;

}

void eraseAllSubStr(std::string & mainStr, const std::string & toErase)
{
	size_t pos = std::string::npos;
	

	// Search for the substring in string in a loop untill nothing is found
	while ((pos = mainStr.find(toErase)) != std::string::npos)
	{
		
		//find the next instance of " after string
		
		
		// If found then erase it from string
		mainStr.erase(pos, toErase.length());
		
		
	}
}

/*
void eraseSubStringsPre(std::string & mainStr, const std::vector<std::string> & strList)
{
	// Iterate over the given list of substrings. For each substring call eraseAllSubStr() to
	// remove its all occurrences from main string.
	for (std::vector<std::string>::const_iterator it = strList.begin(); it != strList.end(); it++)
	{
		eraseAllSubStr(mainStr, *it);
	}

}*/

[Jclow]

Getting closer to the solution, I think VS 2017 sillysense was acting up before, this seems to almost do it.

void eraseAllSubStr(std::string & mainStr, const std::string & toErase)
{
	size_t pos = std::string::npos;
	size_t pos2 = std::string::npos;

	// Search for the substring in string in a loop untill nothing is found
	while ((pos = mainStr.find(toErase)) != std::string::npos)
	{
		
		//find the next instance of " after string
		pos2 = mainStr.find("\"", (pos+10));
		int eraselength = (pos2 - pos);
		std::cout << eraselength;
		// If found then erase it from string
		//mainStr.erase(pos, toErase.length());
		mainStr.erase(pos, eraselength);
		
	}
}

[Jclow]

I worked it out. Hope someone else finds this useful.

void eraseAllSubStr(std::string & mainStr, const std::string & toErase)
{
	size_t pos = std::string::npos;
	size_t pos2 = std::string::npos;

	// Search for the substring in string in a loop untill nothing is found
	while ((pos = mainStr.find(toErase)) != std::string::npos)
	{
		
		//find the next instance of " after string
		//int originaleraselength = toErase.length();
		pos2 = mainStr.find("\"", (pos+ toErase.length()));
		int eraselength = ((pos2+1) - pos);
		std::cout << eraselength;
		// If found then erase it from string
		//mainStr.erase(pos, toErase.length());
		mainStr.erase(pos, eraselength);
		
	}
}