4 replies to this topic

[Macoder]

I've looked all over, and I've found several ways to do this, but none seem to work right. Here's what I'm at so far:

#include <iostream>

#include <vector>

#include <string>


using namespace std;


int main (int argc, char * const argv[]) {

    vector<string> words;

	int vectorlength = 0;

	

	string input;

	cout << "Enter \"done\" when done.\n";

	cin >> input;

	while (input.compare("done") != 0);

	{

		vectorlength++;

		words.resize(vectorlength, input);

		cin >> input;

	}

    return 0;

}

What I'm trying to do is store string values into a vector until the user enters done. But right now they can enter whatever they want and when they enter done, nothing happens. The cursor just moves to a new line. What's really strange is that if the first thing you enter is "done" and then you enter something else after it, the program quits.

Does anyone know why this is happening?

[dargueta]

while (input.compare("done") != 0)[B][COLOR="red"][U];[/U][/COLOR][/B]

{

	vectorlength++;

	words.resize(vectorlength, input);

	std::cin >> input;

}

Might want to get rid of that semicolon. :)

Edited by dargueta, 14 July 2011 - 04:41 PM.

[Macoder]

dargueta said:

Might want to get rid of that semicolon. :)

Oh. Duh. It works now. Is adding the semicolon some feature? Because it has a very unique way of functioning with it.

[Alexander]

Macoder said:

Oh. Duh. It works now. Is adding the semicolon some feature? Because it has a very unique way of functioning with it.

You've an infinite loop if you do not enter "done"

The semicolon will end the statement, so if input is not "done" then it will infinitely compare input to "done" and do nothing.

The braces afterwards {} are unique to C++, and will define its own scope. For example if a variable is defined within those braces it will deallocate afterwards. This is why if you enter "done" and then another thing it will quit, the code within the brace has finished.

It must be connected with the while() statement to have that code ran each loop, rather than just the comparison each time.

[dargueta]

You can have the same problem with for and if statements as well - be careful!