Star Pattern in C++

Three star pyramids in one C++ file: right-half, left-half, full. Same loops as the beginner pattern pages.

IntermediateAdvanced Pattern ProgramsExample 1 of 6

star-pattern.cpp

1#include <iostream>
2using namespace std;
3
4int main() {
5    int rows;
6    
7    cout << "Enter number of rows: ";
8    cin >> rows;
9    
10    // Right Half Pyramid
11    cout << "\nRight Half Pyramid:" << endl;
12    for (int i = 1; i <= rows; i++) {
13        for (int j = 1; j <= i; j++) {
14            cout << "* ";
15        }
16        cout << endl;
17    }
18    
19    // Left Half Pyramid
20    cout << "\nLeft Half Pyramid:" << endl;
21    for (int i = 1; i <= rows; i++) {
22        for (int j = 1; j <= rows - i; j++) {
23            cout << "  ";
24        }
25        for (int j = 1; j <= i; j++) {
26            cout << "* ";
27        }
28        cout << endl;
29    }
30    
31    // Full Pyramid
32    cout << "\nFull Pyramid:" << endl;
33    for (int i = 1; i <= rows; i++) {
34        for (int j = 1; j <= rows - i; j++) {
35            cout << " ";
36        }
37        for (int j = 1; j <= 2 * i - 1; j++) {
38            cout << "*";
39        }
40        cout << endl;
41    }
42    
43    return 0;
44}

Output

Enter number of rows: 5

Right Half Pyramid:
*
* *
* * *
* * * *
* * * * *

Left Half Pyramid:
        *
      * *
    * * *
  * * * *
* * * * *

Full Pyramid:
    *
   ***
  *****
 *******
*********

What's going on

One file, three pyramids you already know from Pattern Programs. rows = 5 in the sample.

Right-half: inner j <= i, "* ". Row i has i stars.

Left-half: pad (rows - i) times with " ", then the same stars. Two spaces per pad so they match "* ".

Full: pad rows - i with " ", then 2 * i - 1 times "*". Odd counts: 1, 3, 5, 7, 9. No space between stars.

Each block prints a label, then endl after the inner loops. Same bugs as the single-pattern pages: < rows drops the last row, " " vs " " leans the left-half.

This page is a cheat sheet. The deep walk is on Right Half / Left Half / Full Pyramid.

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