creating a hollow rectangle - c++

Question

My assignment is to allow for user input of width, height, and character, in order to create a hollow rectangle. I am hitting a wall in my coding, For some reason, my rectangle doesn't have a "top" and the right side isn't on the correct column. I am fairly new to C++, so any criticism you may have is welcomed!
Below is my code and the output that I receive.
#include <iostream>
using namespace std;
int main()
{
int i, j, height, width;
char ch;
char cont ='Y';
while (cont=='Y' || cont=='y')
{
cout << "Enter desired height (3 to 20): ";
cin >> height;
while (height > 20 || height < 3 )
{
cout<<"Illegal entry. Please enter height value from 3 to 20: ";
cin >> height;
}
cout <<"Enter desired width (3 to 20): ";
cin >> width;
while (width > 20 || width < 3)
{
cout<<"Illegal entry. Please enter width value from 3 to 20: ";
cin >> width;
}
cout << "What character would you like to set as your border?: ";
cin >> ch;
for(int i = 1; i <= height; i++) {
if(width <= 1)
for(int i = 1; i <=width; i++) {
cout << " " << ch;
}
else if(i < height) {
cout << endl;
for(int j = 1; j <= width; j++) {
if(j == 1 || j == width)
cout << " " << ch;
else
cout << " ";
}
}
else {
cout<< endl;
for(int k = 1; k <= width; k++)
{
cout <<" "<< ch;
}
}
}
cout<<"\nDo you want to continue? (Y): ";
cin >> cont;
}
cout <<"\nYou are done here, good job.\n";
cout <<'\n';
}

Answer 1

While I won't get into the code itself, think about what you want to accomplish first, and then write the loops. (I suggest using row and col as variable names.)
Since you need a hollow rectangle and you are taking in a desired width and height we know the following (w and h being input amounts.)
So do the following prints in order:
You need a row of * with length w.
You need h - 2 rows of * that have w - 2 spaces between them.
You need another row like 1.
Do these in order and you will have your hollow rectangle.
Example input: w = 5, h = 7.
So we have:
***** // Step 1.
* * // Step 2. Note there are 5 - 2 spaces between them. (w - 2).
* *
* *
* *
* *
***** // Step 3.

Answer 2

While you already have a good answer, you are not making use of the C++ language functions that would make the task much easier, and more importantly, you are not validating your input correctly. For example, try the following:
> McNiel CSC 2050.exe
Enter desired height (3 to 20): No, I don't think I will
Things go wildly spinning out of control quickly.
Generally, when you want to validate user input and ensure you receive values within a specific range, you simply want a continual loop, where you prompt, validate the input, check/handle the stream states .eof(), .bad() and .fail() (see: std::basic_iostream) and empty any remaining characters in your input buffer before your next read attempt.
An example for your h x w input loop would be similar to the following (note, both h and w are read at the same time, you are free to use two loops if you like):
int h, w;
for (;;) {
std::cout << "enter height & width (3 <= h w <= 20): ";
if (!(std::cin >> h >> w)) {
if (std::cin.eof() || std::cin.bad()) {
std::cerr << "(user canceled/unrecoverable error)\n";
return 1;
}
else if (std::cin.fail()) {
std::cerr << "error: invalid integer input.\n";
std::cin.clear();
std::cin.ignore (std::numeric_limits<std::streamsize>::max(),'\n');
}
}
else if (3 <= h && h <=20 && 3 <= w && w <= 20)
break;
else
std::cerr << "error: h or w not within (3 <= x <= 20)\n";
}
See std::basic_istream::ignore for details on emptying the input stream and std::basic_ios::clear.
Next, rather than some loop scheme outputting spaces, you simply need to make use of std::setw to handle the spacing between the '*' to make your hollow rectangle. The top and bottom are solid, but for the middle rows, all you need to do is std::cout << '*' << std:setw(w-1) << '*';. For example your entire output loop reduces to:
for (int i = 0; i < h; i++) {
if (!i || i == h - 1)
for (int j = 0; j < w; j++)
std::cout << '*';
else
std::cout << '*' << std::setw(w-1) << '*';
std::cout << '\n';
}
Putting it altogether, you can do something similar to the following:
#include <iostream>
#include <iomanip>
#include <limits>
int main (void) {
int h, w;
for (;;) {
std::cout << "enter height & width (3 <= h w <= 20): ";
if (!(std::cin >> h >> w)) {
if (std::cin.eof() || std::cin.bad()) {
std::cerr << "(user canceled/unrecoverable error)\n";
return 1;
}
else if (std::cin.fail()) {
std::cerr << "error: invalid integer input.\n";
std::cin.clear();
std::cin.ignore (std::numeric_limits<std::streamsize>::max(),'\n');
}
}
else if (3 <= h && h <=20 && 3 <= w && w <= 20)
break;
else
std::cerr << "error: h or w not within (3 <= x <= 20)\n";
}
for (int i = 0; i < h; i++) {
if (!i || i == h - 1)
for (int j = 0; j < w; j++)
std::cout << '*';
else
std::cout << '*' << std::setw(w-1) << '*';
std::cout << '\n';
}
}
Example Use/Output
$ ./bin/hollowrect
enter height & width (3 <= h w <= 20): No, I don't think I will
error: invalid integer input.
enter height & width (3 <= h w <= 20): OK
error: invalid integer input.
enter height & width (3 <= h w <= 20): 10 2
error: h or w not within (3 <= x <= 20)
enter height & width (3 <= h w <= 20): 10 3
***
* *
* *
* *
* *
* *
* *
* *
* *
***
A second h x w example:
$ ./bin/hollowrect
enter height & width (3 <= h w <= 20): 3 10
**********
* *
**********
User cancels with manual EOF:
$ ./bin/hollowrect
enter height & width (3 <= h w <= 20): help
error: invalid integer input.
enter height & width (3 <= h w <= 20): (user canceled/unrecoverable error)
Look things over and let me know if you have further questions.

Answer 3

if you want to below result when assign height and width is 4.
* * * *
* *
* *
* * * *
your for loop is wrong, using this code in your for loop.
for(int i = 1; i <= height; i++) {
if( i == 1 || i == height) {
for (int j = 1; j <= width; j++) {
std::cout << ch << " ";
}
std::cout << std::endl;
} else {
for (int j = 1; j <= width; j++) {
if( j == 1 || j == width) {
std::cout << ch << " ";
} else {
std::cout << " ";
}
}
std::cout << std::endl;
}
}