Function for a rectangle

[wizegamot]

I'm in my first quarter working on my third C++ project and it's very tough for me. My program displays a grid of 20 rows by 30 columns and I am required to design functions that plot shapes on the grid. I've created a test for them below. How do I call the plotVerticalLine and the plotHorizontalLine functions to create a function to plot a rectangle?
-----------------------------------------------------------------
ifndef GRAPHLIB_H
define GRAPHLIB_H
// Graphics library interface
const int NROWS = 20;
const int NCOLS = 30;
--------------------------------------------------------------------

void clearGrid();
void setChar(int r, int c, char ch);
char getChar(int r, int c);
void draw();
endif / GRAPHLIB_H /
include "graphlib.h"
include <iostream>
include <iomanip>
include <string>
include <cstdlib>
include <cctype>
using namespace std;
char grid[NROWS][NCOLS]; bool isGridInitialized = false;
void drawHorizBorder(); void checkPos(int r, int c, string func);
void clearGrid() {
for (int r = 0; r < NROWS; r++)
for (int c = 0; c < NCOLS; c++)
grid[r][c] = ' ';
isGridInitialized = true;
}
void setChar(int r, int c, char ch) {
checkPos(r, c, "setChar");
grid[r-1][c-1] = ch;
}
char getChar(int r, int c) {
checkPos(r, c, "getChar");
return grid[r-1][c-1];
}
void draw() {
// Write header lines of column numbers

cout << " ";
for (int c = 1; c <= NCOLS; c++)
{
int t = c / 10;
if (t == 0)
cout << ' ';
else
cout << t;
}
cout << "\n ";
for (int c = 1; c <= NCOLS; c++)
cout << (c%10);
cout << "\n";

// Draw grid

drawHorizBorder();
for (int r = 1; r <= NROWS; r++)
{
cout << setw(2) << r << '|';
for (int c = 1; c <= NCOLS; c++)
{
char ch = grid[r-1][c-1];
if (isprint(ch))
cout << ch;
else
cout << '?';
}
cout << "|\n";
}
drawHorizBorder();
}
void drawHorizBorder() {
cout << " +";
for (int c = 1; c <= NCOLS; c++)
cout << '-';
cout << "+\n";
}
void checkPos(int r, int c, string func) {
if (!isGridInitialized)
{
cout << func << ": You must first call clearGrid." << endl;
exit(1);
}
if (r < 1 || r > NROWS || c < 1 || c > NCOLS)
{
cout << func << ": invalid position (" << r << "," << c << ")"
<< endl;
exit(1);
}
}

-----------------------------------------------------------------------------------
include "graphlib.h"
include <iostream>
include <string>
using namespace std;
int r, c, l; char ch; string cmd;
void setChar(int r, int c, char ch);
void plotHorizontalLine(int r, int c, int l, char ch);


int main() {
clearGrid();

cout << "Enter command string: ";
getline(cin, cmd);

if (cmd == "")
{
return 0;
}
if (cmd == "h")
plotHorizontalLine(10, 10, 10, '-');

draw();

}


void plotHorizontalLine(int r, int c, int l, char ch)
{
for (int k = 1; k <= l; k++)
{
setChar(r, c+k, ch);
}
}
void plotVerticalLine(int r, int c, int l, char ch)
{
for (int k = 1; k <= l; k++)
{
setChar(r+k, c, ch);
}
}

[sorthon123]

people like it more when you put the code in the code box it looks like <> under the format part

ifndef GRAPHLIB_H
define GRAPHLIB_H
// Graphics library interface
const int NROWS = 20;
const int NCOLS = 30;
--------------------------------------------------------------------

void clearGrid();
void setChar(int r, int c, char ch);
char getChar(int r, int c);
void draw();
endif / GRAPHLIB_H /
include "graphlib.h"
include <iostream>
include <iomanip>
include <string>
include <cstdlib>
include <cctype>
using namespace std;
char grid[NROWS][NCOLS]; bool isGridInitialized = false;
void drawHorizBorder(); void checkPos(int r, int c, string func);
void clearGrid() {
for (int r = 0; r < NROWS; r++)
for (int c = 0; c < NCOLS; c++)
grid[r][c] = ' ';
isGridInitialized = true;
}
void setChar(int r, int c, char ch) {
checkPos(r, c, "setChar");
grid[r-1][c-1] = ch;
}
char getChar(int r, int c) {
checkPos(r, c, "getChar");
return grid[r-1][c-1];
}
void draw() {
// Write header lines of column numbers

cout << " ";
for (int c = 1; c <= NCOLS; c++)
{
int t = c / 10;
if (t == 0)
cout << ' ';
else
cout << t;
}
cout << "\n ";
for (int c = 1; c <= NCOLS; c++)
cout << (c%10);
cout << "\n";

// Draw grid

drawHorizBorder();
for (int r = 1; r <= NROWS; r++)
{
cout << setw(2) << r << '|';
for (int c = 1; c <= NCOLS; c++)
{
char ch = grid[r-1][c-1];
if (isprint(ch))
cout << ch;
else
cout << '?';
}
cout << "|\n";
}
drawHorizBorder();
}
void drawHorizBorder() {
cout << " +";
for (int c = 1; c <= NCOLS; c++)
cout << '-';
cout << "+\n";
}
void checkPos(int r, int c, string func) {
if (!isGridInitialized)
{
cout << func << ": You must first call clearGrid." << endl;
exit(1);
}
if (r < 1 || r > NROWS || c < 1 || c > NCOLS)
{
cout << func << ": invalid position (" << r << "," << c << ")"
<< endl;
exit(1);
}
}

-----------------------------------------------------------------------------------
include "graphlib.h"
include <iostream>
include <string>
using namespace std;
int r, c, l; char ch; string cmd;
void setChar(int r, int c, char ch);
void plotHorizontalLine(int r, int c, int l, char ch);


int main() {
clearGrid();

cout << "Enter command string: ";
getline(cin, cmd);

if (cmd == "")
{
return 0;
}
if (cmd == "h")
plotHorizontalLine(10, 10, 10, '-');

draw(); 

}


void plotHorizontalLine(int r, int c, int l, char ch) 
{ 
for (int k = 1; k <= l; k++) 
{
setChar(r, c+k, ch);
} 
}
void plotVerticalLine(int r, int c, int l, char ch) 
{ 
for (int k = 1; k <= l; k++) 
{
setChar(r+k, c, ch);
} 
}