user input, what's wrong with this?

[noble]

I'm using the following bit of code to get user input. the command
/q should make the program exit but it's not working correctly.
what am i doing wrong?

const unsigned int MAX_SIZE = 256;
char pszCmd[MAX_SIZE] = "";

do
{
cin.getline(pszCmd, MAX_SIZE, '\n');
cout << pszCmd << endl;
}while(pszCmd != "/q");

[HarryW]

This is one of those things about C that makes you appreciate high-level programming languages

As far as the compiler is concerned, any string literal that you put in your code will become a pointer to a sequence of bytes in the executable that your compiler produces from your code. So whenever you write "blah blah blah" the compiler is treating it as a variable of type char*, just a simple pointer.

What this means is that something like this doesn't work:

char *szString = "Hello";

... //some more code might be in-between

if ( szString == "Hello" )
{
    //blah blah some more code
}
//etc

When you check string equality using '==' between two char* expressions, it checks the pointer, not the content of the string. So in this case you actually have two instances of a string "Hello" in your compiled code, and each will have their own address in memory when the code is loaded up. "Hello" == "Hello" will always be false unless you have some weird compiler that decides to optimise by only having one instance of identical strings.

Hey, I just thought, maybe that's what string tables are for... hmm... I never did see the point in them

Anyway, that's the explanation, probably a little more than you needed but what the hey. Now for the solution:

a) use strcmp() (available in string.h) to compare the two strings properly

or

b) if you're coding in C++, use a string class like the STL std::string class to make things much more high-level and easier to manage, at the expense of a little overhead.

[noble]

thx, i'm using strcmp(), it works great although it's weird how
cin.getline interrupts a carriage return.

for some reason, you have to hit return twice for getline to stop
getting data from the user after the "/q" is reached.

any way to remedy this?

[noble]

interprets not interrupts

[CornedBee]

#include <iostream>
#include <cstring>
using namespace std;

int main()
{
    const unsigned int MAX = 256;
    char pszCmd[MAX];

    do
    {
        cin.getline(pszCmd, MAX, '\n');
        cout << pszCmd << endl;
    } while(strcmp(pszCmd, "/q"));
    return 0;
} 

Works without problems, no "hit enter twice" or such.