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