Printing a grid - c++

Question

I want to print a game board grid which will vary in size depending on what the user inputs. I also wanted to know would it be best or even be possible to make this same grid using an array or would I need some type of 2d array of some sort?
void printGrid(int &userRows, int &userColumns){
cout << "Enter the number of rows -> ";
cin >> userRows;
cout << "Enter the number of columns -> ";
cin >> userColumns;
for(int i = 0; i < userColumns; i++){
cout << "|";
for(int y = 0; y < userRows; y++){
cout << "-";
}
}
}
I got the nested loop part down pat. Just having an issue telling it to print a new line and to spawn one after the other. Thank you
Here is the final product I am going for

Answer 1

I got the nested loop part down pat. Just having an issue telling it to print a new line and to spawn one after the other.
Are you sure? That doesn't seem to produce anything close to the final product I am going for?
While that may produce "|" and "-" output, it ignores the column headings, the header separator, the row labels, the footer separator and the column footer.
In answer to the newline part of your question, you have two options, you can either output a newline with the macro endl or you can output a literal newline "\n". If you have declared using namespace std;, you can simply use the cout << endl; or cout << "\n";. otherwise you need to explicitly specify the std namespace, e.g. std::cout << endl; or std::cout << "\n";
To finish building your output with column heading, separators, row labels, footer separator and footer, just take it piece-by-piece. For example for your column headings, you could simply loop over your columns, outputting your loop counter + 1 with appropriate spacings:
for (int i = 0; i < cols; i++) /* output column headings */
if (!i)
std::cout <<" " << i+1;
else
std::cout <<" " << i+1;
std::cout << "\n";
(note: the use of the if (!i) (equivalent to if (i == 0)) to handle the first-column spacing separately)
For your heading separator, you could loop over the columns again, in like manner with the same check handling the first column differently.
for (int i = 0; i < cols; i++) /* output header separators */
if (!i)
std::cout <<" ---";
else
std::cout <<" ---";
std::cout << "\n";
Then the actual grid sections requires row-labels both before, and after, each row of the grid is output. Here you simply add a nested loop to loop over each row, but otherwise use a similar loop over each column with first row check, followed by a final output of the closing row-label for each row:
for (int i = 0; i < rows; i++) { /* output labeled grid rows */
for (int j = 0; j < cols; j++)
if (!j)
std::cout << (char)('A' + i) << " | |";
else
std::cout << " |";
std::cout << " " << (char)('A' + i) << "\n";
}
Finally, you just repeat what you did for the column headers and header separator in reverse order for your footer separator and footer, outputting the separator row first followed by the column footers, e.g.
for (int i = 0; i < cols; i++) /* output footer separators */
if (!i)
std::cout <<" ---";
else
std::cout <<" ---";
std::cout << "\n";
for (int i = 0; i < cols; i++) /* output column footer */
if (!i)
std::cout <<" " << i+1;
else
std::cout <<" " << i+1;
std::cout << "\n"; /* tidy up with new line */
That's pretty much it. You can throw together a short example using a class board to hold the rows and cols values and a constructor and a couple of member functions to update or request input for new row/column values, e.g. the following just outputs your 4x6 grid, then prompts for new rows and cols values, and finally output a 5x7 example:
#include <iostream>
class board {
int rows, cols;
public:
board() {};
board (int x, int y) { rows = x; cols = y; }
void prngrid ();
void setsize (int x, int y) { rows = x; cols = y; }
void setsize ();
};
void board::prngrid ()
{
std::cout << "\n"; /* output new line before grid */
for (int i = 0; i < cols; i++) /* output column headings */
if (!i)
std::cout <<" " << i+1;
else
std::cout <<" " << i+1;
std::cout << "\n";
for (int i = 0; i < cols; i++) /* output header separators */
if (!i)
std::cout <<" ---";
else
std::cout <<" ---";
std::cout << "\n";
for (int i = 0; i < rows; i++) { /* output labeled grid rows */
for (int j = 0; j < cols; j++)
if (!j)
std::cout << (char)('A' + i) << " | |";
else
std::cout << " |";
std::cout << " " << (char)('A' + i) << "\n";
}
for (int i = 0; i < cols; i++) /* output footer separators */
if (!i)
std::cout <<" ---";
else
std::cout <<" ---";
std::cout << "\n";
for (int i = 0; i < cols; i++) /* output column footer */
if (!i)
std::cout <<" " << i+1;
else
std::cout <<" " << i+1;
std::cout << "\n"; /* tidy up with new line */
}
void board::setsize ()
{
std::cout << "\nenter the number of rows -> ";
std::cin >> rows;
std::cout << "enter the number of cols -> ";
std::cin >> cols;
}
int main (void) {
board board1 (4, 6);
board1.prngrid();
board1.setsize();
board1.prngrid();
board1.setsize (5,7);
board1.prngrid();
return 0;
}
(note: you should add validation checks that rows and cols values are non-negative (or choose an unsigned type), and also check that they are reasonable for your screen output (e.g. less than 20 or so and at least 26 or less or you will run out of upper-case letters). Those checks, and adjustments for multi-digit headings, are left to you)
Example Use/Output
$ ./bin/board_grid
1 2 3 4 5 6
--- --- --- --- --- ---
A | | | | | | | A
B | | | | | | | B
C | | | | | | | C
D | | | | | | | D
--- --- --- --- --- ---
1 2 3 4 5 6
enter the number of rows -> 5
enter the number of cols -> 5
1 2 3 4 5
--- --- --- --- ---
A | | | | | | A
B | | | | | | B
C | | | | | | C
D | | | | | | D
E | | | | | | E
--- --- --- --- ---
1 2 3 4 5
1 2 3 4 5 6 7
--- --- --- --- --- --- ---
A | | | | | | | | A
B | | | | | | | | B
C | | | | | | | | C
D | | | | | | | | D
E | | | | | | | | E
--- --- --- --- --- --- ---
1 2 3 4 5 6 7
Look things over and let me know if you have further questions.

Answer 2

The problem is fairly easy, just understand the pattern! Here's the working code with live example.
#include <iostream>
using namespace std;
void printGrid(int &userRows, int &userColumns){
cout<<endl;
cout<<" ";
int i=1,j;
for(j = 0; j <= 4*userColumns; j++){
if(j%4==2)
cout<<i++;
else cout<<" ";
}
cout<<endl;
for(i = 0; i <= 2*userRows; i++){
if(i%2!=0)
cout<<(char)(i/2 +'A');
for(j = 0; j <= 2*userColumns; j++){
if(i%2==0)
{
if(j==0)
cout<<" ";
if(j%2==0)
cout<<" ";
else cout<<"---";
}
else{
if(j%2==0)
cout<<"|";
else cout<<" ";
}
}
if(i%2!=0)
cout<<(char)(i/2 +'A');
cout<<endl;
}
cout<<" ";
for(j = 0, i = 1; j <= 4*userColumns; j++){
if(j%4==2)
cout<<i++;
else cout<<" ";
}
cout<<endl;
}
int main() {
int userRows, userColumns;
cout << "Enter the number of rows -> ";
cin >> userRows;
cout << "Enter the number of columns -> ";
cin >> userColumns;
printGrid(userRows, userColumns);
return 0;
}
Live Code
Output:
Enter the number of rows -> 4
Enter the number of columns -> 6
1 2 3 4 5 6
--- --- --- --- --- ---
A| | | | | | |A
--- --- --- --- --- ---
B| | | | | | |B
--- --- --- --- --- ---
C| | | | | | |C
--- --- --- --- --- ---
D| | | | | | |D
--- --- --- --- --- ---
1 2 3 4 5 6

Answer 3

By adding the cout << endl; after the userRows for-loop has finish the process it will proceed with the next line until i < userColumns
for(int i = 0; i < userColumns; i++){
cout << "|";
for(int y = 0; y < userRows; y++){
cout << "-";
}
cout << endl; //end of every-line
}

Answer 4

When you say:
make this same grid using an array
I'm guessing you are asking how to handle values you can use to populate the grid. There are lots of ways to store a variable number of values. Here are a few (I'm assuming the values are of type char):
One dimensional std::vector
std::vector<char> gridValues;
gridValues.resize(userColumns * userRows);
Then, inside the for loops:
cout << gridValues.at( i + y*userColumns );
Two dimensional std::vector
std::vector<std::vector<char>> gridValues;
gridValues.resize(userRows);
for( int i = 0; i < userRows; ++i )
gridValues.at(i).resize(userColumns);
Then, inside the for loops:
cout << gridValues.at( y ).at( i );
One dimensional array
char* gridValues = new char[ userColumns*userRows ];
Then, inside the for loops:
cout << gridValues[ i + y*userColumns ];
Two dimensional array
char** gridValues = new char[ userRows ];
for( int i = 0; i < userRows; ++i )
gridValues[i] = new char[ userColumns ];
Then, inside the for loops:
cout << gridValues[ y ][ i ];
I would use the one-dimensional std::vector, because it's simple to setup and I don't have to worry about forgetting to delete the pointers at the end.
As a note, you may want to check you for loops. With userColumns = 3 and userRows = 2, the code you gave will print: |--|--|--. The variables are being used backwards.
Once you fix the order of the loops, JaxLee's answer will help you put the newline in the right spot.