How do you make a rectangle and triangle shape in C++

Question

How do i achieve this format when i keyed in int of ' 245 ':

(where if it is odd number it will be a rectangle, and even number will be triangle)

 1
 1 2

 1 
 1 2
 1 2 3
 1 2 3 4

 1 2 3 4 5
 1 2 3 4 5
 1 2 3 4 5
 1 2 3 4 5
 1 2 3 4 5

This is my code so far:

(I can't seemed to output triangle and rectangle at the same time)

int n;
int lastDigit;

do
{
    cout << "Enter a positive integer: ";
    cin >> n;

}while ( n <= 1 || n == '0');

cout << endl;

// If even digit - tri
do
{
    lastDigit = n%10;

    if (lastDigit / 2 ==0)
    {
        for (int i = 1; i <= lastDigit; ++i)
            for (int tri = 1; tri <= i; ++tri)
                cout << "\t" << tri;

        cout << endl;
    }

    // if odd digit - rect
    else if (lastDigit / 2 != 0)
    {
        for (int i = 1; i <= lastDigit; i++)
        {
            for (int rect = 1; rect <= i; rect++)
                cout << "\t" << rect;

            cout << endl;
        }
        n = n/10;
    }

    cout << endl;

}while (lastDigit != 0);

n = n/10;
cout << endl;

return 0;

And, how should i code when keyed in the int, the compiler will extract the first digit (From left to right) and output it accordingly?

Any help would be appreciated!

Answer 1

Following is the complete code.

Step1 : Take user input and check whether it's odd or even.

Step2 : If it is odd then perform triangle else rectangle.

#include<iostream>
int main () {

int n;

cout<<"Enter number: ";
cin>>n;

if (n % 2 != 0)
{
    for(int i = 1; i <= n; i++)
    {
        cout<<endl;
        for(int j = 1; j <= n; j++)
        {
            cout<<j<<" ";
        }
    }
}
else
{
    for(int i = 1; i <= n; i++)
    {
        cout<<endl;
        for(int j = 1; j <= i; j++)
        {
            cout<<j<<" ";
        }
    }
}

return 0; 
}

Answer 2

Both of your print is similar. I suggest:

#include<iostream>

using namespace std;

int main () {

    int n;

    cout << "Enter number: ";
    cin >> n;

    int i = 1;
    int& rowLim = ((n % 2) ? n : i);

    for(i = 1; i <= n; i++)
    {
        cout << endl;
        for(int j = 1; j <= rowLim; j++)
        {
            cout<<j<<" ";
        }
    }

    return 0; 

}

Answer 3

Simplest would be to use a string , iterate char by char and output accordingly. For instance

#include <iostream>
using namespace std;

int main() {
    string s;
    cin >> s;
    for (char c : s) {
        int n = c - '0';
        bool k = n % 2;
        for (int i = 1; i <= n; ++i) {
            for (int j = 1; j <= (k ? n : i); ++j)
                cout << " " << j;
            cout << endl;
        }
        cout << endl;
    }
    return 0; 
}

Output

 1
 1 2

 1
 1 2
 1 2 3
 1 2 3 4

 1 2 3 4 5
 1 2 3 4 5
 1 2 3 4 5
 1 2 3 4 5
 1 2 3 4 5

See a DEMO