20 Pattern Programs in C++

Five star patterns in one C++ file (right, left, full, inverted, diamond). rows is hardcoded to 5.

IntermediateAdvanced Pattern ProgramsExample 6 of 6

20-pattern-programs.cpp

1#include <iostream>
2using namespace std;
3
4int main() {
5    int rows = 5;
6    
7    // Pattern 1: Right Half Pyramid
8    cout << "Pattern 1 - Right Half Pyramid:" << endl;
9    for (int i = 1; i <= rows; i++) {
10        for (int j = 1; j <= i; j++) {
11            cout << "* ";
12        }
13        cout << endl;
14    }
15    
16    // Pattern 2: Left Half Pyramid
17    cout << "\nPattern 2 - Left Half Pyramid:" << endl;
18    for (int i = 1; i <= rows; i++) {
19        for (int j = 1; j <= rows - i; j++) {
20            cout << "  ";
21        }
22        for (int j = 1; j <= i; j++) {
23            cout << "* ";
24        }
25        cout << endl;
26    }
27    
28    // Pattern 3: Full Pyramid
29    cout << "\nPattern 3 - Full Pyramid:" << endl;
30    for (int i = 1; i <= rows; i++) {
31        for (int j = 1; j <= rows - i; j++) {
32            cout << " ";
33        }
34        for (int j = 1; j <= 2 * i - 1; j++) {
35            cout << "*";
36        }
37        cout << endl;
38    }
39    
40    // Pattern 4: Inverted Pyramid
41    cout << "\nPattern 4 - Inverted Pyramid:" << endl;
42    for (int i = rows; i >= 1; i--) {
43        for (int j = 1; j <= rows - i; j++) {
44            cout << " ";
45        }
46        for (int j = 1; j <= 2 * i - 1; j++) {
47            cout << "*";
48        }
49        cout << endl;
50    }
51    
52    // Pattern 5: Diamond
53    cout << "\nPattern 5 - Diamond:" << endl;
54    for (int i = 1; i <= rows; i++) {
55        for (int j = 1; j <= rows - i; j++) {
56            cout << " ";
57        }
58        for (int j = 1; j <= 2 * i - 1; j++) {
59            cout << "*";
60        }
61        cout << endl;
62    }
63    for (int i = rows - 1; i >= 1; i--) {
64        for (int j = 1; j <= rows - i; j++) {
65            cout << " ";
66        }
67        for (int j = 1; j <= 2 * i - 1; j++) {
68            cout << "*";
69        }
70        cout << endl;
71    }
72    
73    return 0;
74}

Output

Pattern 1 - Right Half Pyramid:
*
* *
* * *
* * * *
* * * * *

Pattern 2 - Left Half Pyramid:
        *
      * *
    * * *
  * * * *
* * * * *

Pattern 3 - Full Pyramid:
    *
   ***
  *****
 *******
*********

Pattern 4 - Inverted Pyramid:
*********
 *******
  *****
   ***
    *

Pattern 5 - Diamond:
    *
   ***
  *****
 *******
*********
 *******
  *****
   ***
    *

What's going on

The file is named like a gallery. The code actually prints five patterns, rows hardcoded to 5. No cin.

1.Right-half: j <= i, "* "

2.Left-half: pad " " (rows - i) times, then stars

3.Full: pad " ", then 2 * i - 1 times "*"

4.Inverted full: i counts down

5.Diamond: full pyramid, then inverted from rows - 1 so the middle isn't doubled

Those are the Pattern Programs pages plus Diamond, concatenated with labels.

Change rows at the top to try 3 or 7. The formulas don't change.

If you came here for twenty separate homeworks, this source only has those five. The earlier pages in this topic (star, triangle, pyramid, number) cover the rest of the usual set.

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