Program Crashes when i modify one of the parameters

I have a function in a class but whenever i try to modify one of the parameters in the function the program crashes.

This is my .h file:

Code:

class InfFiles
{
public:
	char* GetValue(char option[50]);
	void  SetValue(char option[50], char Value[50]);
	char  fileName[100];
};

This is my code for the GetValue() function:

Code:

#include <windows.h>
#include <fstream.h>
#include "class - inf.h"

char* InfFiles::GetValue(char option[50])
{
	ifstream file;
	file.open(fileName, ios::in);

	char searchResult[100];
	int  size = strlen(option);
	bool optionFound = false;
	while(!file.eof())
	{
		file.getline(searchResult, 100);
		searchResult[size] = NULL;
		if(strcmp(option, searchResult)==0)
		{
			optionFound = true;
			return searchResult;
		}
	}
	return NULL;
}

If i put "strcat(option, " = ");" or "option[0] = NULL" into the GetValue function the program will crash. Also if the GetValue function returns "option" i get a returned value but if it returns "searchResult" it just returns NULL.

Please help me
thanks

>>char searchResult[100];
You try to return a pointer to a local variable, this won't work because searchResult is destroyed when the function returns, there's nothing to point to but garbage.

>>searchResult[size] = NULL;
You shouldn't confuse NULL with '\0', they may be equivalent but using NULL might kill things too, better to be safe :-)

>>If i put "strcat(option, " = ");" or "option[0] = NULL" into the GetValue function the program will crash.
My best guess is that option is a string literal and is in read only memory. When you try to modify it, you get an access violation.

A stylistic note, member variables are usually private in a class and member functions public. Why this is so has been written about many times, so a quick google search (or looking around on this site) should reveal some answers. I'm not saying your code is wrong in anyway, just that you should get into the habit of it.