Error with std::out_of_range, Can someone help?

[dude2333]

Here is the console:

varr HelloWorld, Hello, world!;
prnt HelloWorld;
quit
terminate called after throwing an instance of 'std::out_of_range'
  what():  basic_string::substr
Aborted (core dumped)
Press ENTER to continue...

here is my main loop of code:

string argv = "";
	string line = "";
	while(line != "quit") {
		cin >> line;
		argv += line;
	}
	
	for(int i = 0; i < sizeof(argv) - 4; i++) {
		if(argv.substr(i, 4) == "varr") {
			string name = "";
			int x = i +1;
			for(x; argv.substr(x) != ","; x++) {
				name += argv.substr(x);
			}
			string val = "";
			x++;
			for(x; argv.substr(x) != ";"; x++) {
				val += argv.substr(x);
			}
			
			vars[name] = val;
			i = x;
		} else if(argv.substr(i, 4) == "prnt") {
			string name = "";
			int x = i +1;
			for(x; argv.substr(x) != ";"; x++) {
				name += argv.substr(x);
			}
			
			cout << vars[name];
			i = x;
		}
	}
	
	cin.get();
	cin.sync();

Okay so now I'm in debug and at that error I get:

Program Received signal SIGABRT
Stack trace is available in the 'Call Stack' tab

[ne555]

http://www.cplusplus.com/forum/general/112111/

[cire]

Your loop condition on line 8 makes no sense. Presumably you meant argv.size() or argv.length() and not sizeof(argv).

[ShodanHo]

My guess is that one of the:

argv.substr(i, 4)
argv.substr(x)

statements is trying to access out of the length of the string.

http://www.cplusplus.com/reference/string/string/substr/
says:

If pos is greater than the string length, an out_of_range exception is thrown.