string and array

[mihai14]

Hi I would like to know what is the problem with this:

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

int main()
{
char square[7][7],x,y;
string command;
//start:
for (x=1;x<9;x++)
{
for (y=1;y<9;y++)
{
square[x][y] = 'x';
}
}
getline(cin,command);
if (command.substr(0,5) == "print")
{
for (x=1;x<9;x++)
{
for (y=1;y<9;y++)
{
cout << square[x][y];
}
cout << "\n";
}
}
}

And what i get is:

xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xx rint
xxxxxxx (there is a space at the begining of this line)

When in my understandin should be a 8x8 block of "x".
I think it'a about memory allocation but couldn't find how to fix it.
Any help would be appreciated.

[freakalien]

You are attempting to access elements of your array that are out of bounds. The 2D array "square" is declared with dimension 7 by 7. The elements of this array may be accessed using square[i][k] where i and k are elements of the set of integers {0,1,2,3,4,5,6}. Try this alternative:

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

int main() {
	char square[7][7];
	int x, y;
	string command;
	for (x=0;x<7;x++) {
		for (y=0;y<7;y++) {
			square[x][y] = 'x';
		}
	}
	getline(cin,command);
	if (command.substr(0,5) == "print") {
		for (x=0;x<7;x++) {
			for (y=0;y<7;y++) {
				cout << square[x][y];
			}
			cout << "\n";
		}
	}
}

[firix]

int main()
{
	char square[7][7];
	string command;
	//start:
	for (int x=0;x<7; x++) {
		for (int y= 0;y < 7; y++) {
			square[x][y] = 'x';
		}
	}
	getline(cin,command);
	if (command.substr(0,5) == "print"){
	   for (int x=0; x<7; x++) {
		   for (int y=0; y<7; y++) {
               cout << square[x][y];
            }
            cout << "\n";
        }
    }

	return 0;
}

I do not understand what you're trying to do.

[mihai14]

Oh... ye the was 2 missing. As I can see the ++ affects before the value is used in the array.
Aren't the values of a [7] array 0, 1 ,2 ,3 ,4 ,5 ,6 ,7?
Thanks that was the problem, as you can notice im new, my 3rd day of learning and maybe a bit tired.

[freakalien]

No, you are missing the point. Read this: http://www.cplusplus.com/doc/tutorial/arrays/

[firix]

good luck :)