Pyramid Program in C++

Full, inverted, and hollow centered pyramids in C++. Hollow uses 2*i-1 and a single-space gap.

IntermediateAdvanced Pattern ProgramsExample 4 of 6

pyramid-program.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    // Full Pyramid
11    cout << "\nFull Pyramid:" << endl;
12    for (int i = 1; i <= rows; i++) {
13        for (int j = 1; j <= rows - i; j++) {
14            cout << " ";
15        }
16        for (int j = 1; j <= 2 * i - 1; j++) {
17            cout << "*";
18        }
19        cout << endl;
20    }
21    
22    // Inverted Pyramid
23    cout << "\nInverted Pyramid:" << endl;
24    for (int i = rows; i >= 1; i--) {
25        for (int j = 1; j <= rows - i; j++) {
26            cout << " ";
27        }
28        for (int j = 1; j <= 2 * i - 1; j++) {
29            cout << "*";
30        }
31        cout << endl;
32    }
33    
34    // Hollow Pyramid
35    cout << "\nHollow Pyramid:" << endl;
36    for (int i = 1; i <= rows; i++) {
37        for (int j = 1; j <= rows - i; j++) {
38            cout << " ";
39        }
40        for (int j = 1; j <= 2 * i - 1; j++) {
41            if (j == 1 || j == 2 * i - 1 || i == rows) {
42                cout << "*";
43            } else {
44                cout << " ";
45            }
46        }
47        cout << endl;
48    }
49    
50    return 0;
51}

Output

Enter number of rows: 5

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

Inverted Pyramid:
*********
 *******
  *****
   ***
    *

Hollow Pyramid:
    *
   * *
  *   *
 *     *
*********

What's going on

Three centered pyramids: full, inverted, hollow. Same 2 * i - 1 star count as Full Pyramid.

Full: i = 1..rows, pad rows - i with " ", then that many "*".

Inverted: i = rows..1, same inners. 9 stars first when rows is 5.

Hollow:

if (j == 1 || j == 2 * i - 1 || i == rows) cout << "*"; else cout << " ";

Left peak, right peak, and the entire base. Interior is a single space — stars here have no trailing space, so the gap is " ", not " ".

Walk 5, hollow:

i=1: one star (both edges are the same cell)

i=2: star, space, star, padded

i=5: nine stars

i == rows missing → the base is two corners. 2 * i without - 1 → even counts and it stops looking like a triangle.

Labels between blocks so the three dumps don't run together.

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