Passing by reference or pointer

[cc89]

Let's say I've got a method called addPoint that accepts an object as an argument like so...

addPoint(Point a(2), Point b(5));

...would this be the correct way of using the addPoint method with pointers?

Point* a = new Point(2);
Point* b = new Point(5);
addPoint(*a, *b);

For me, the above only works if the Point objects are initialized inside the same method as addPoint. If I initialize them in a constructor and then try using addPoint in another method, the program segfaults.

Line::Line()
{
   a = new Point(2); //header file: Point* a;
   b = new Point(5); //header file: Point *b;
}

int Line::getAddedPoints()
{
   addPoints(*a, *b); //segfaults
}

int Line::getAddedPoints2()
{
   a = new Point(2);
   b = new Point(5);
   addPoints(*a, *b); //works fine
}

[firedraco]

I suppose, but you need to remember to delete them when you are done...however, if a and b are members of the Line class, then getAddedPoints() shouldn't segfault unless you are doing something weird. What does addPoints() look like?

[S6k9GNh0]

http://codepad.org/jyCndoXZ

The above is a running example of something similar to what you've described. I unfortunately cannot pinpoint the exact location the segfault would happen without more information.

[cc89]

Well, I'm actually working with a tr1::regex class. Here's the actual code that's giving me the problem. I've stripped out everything that wasn't necessary and pointed out exactly where it segfaults.

#include "stdafx.h"
#include "Parser.h"

Parser::Parser()
{
	patternA = new tr1::regex("testA");
	patternB = new tr1::regex("testB");
        patternC = new tr1::regex("testC");
        //etc...
}

string Parser::getMatchA(string str)
{
	return findmatch(str, patternA);
}

string Parser::getMatchB(string str)
{
	return findmatch(str, patternB);
}

string Parser::getMatchC(string str)
{
	return findmatch(str, patternC);
}
//etc...

//private method
string Parser::findmatch(string str, tr1::regex* pattern)
{
	tr1::smatch result;
	if (tr1::regex_search(str, result, *pattern)) //segfaults here
		return result[1];                     //does not segfault if '*pattern' is replaced with 'tr1::regex("test")'
	else
		return "";
}

When I do a getMatch method, the program segfaults. Otherwise if I do it within a try-catch block, I get an exception along the lines of "corrupt pattern". The actual patterns I'm using have been tested, so I'm sure that they aren't corrupt.