Center-Aligned Pyramid Star Pattern in C++

What You’ll Learn

A center-aligned pyramid combines leading spaces with odd star counts: (rows - i) spaces and (2 * i - 1) stars on row i. This tutorial covers the centering formula, why odd widths matter, a live preview, algorithm steps, worked C++ examples, edge cases, and complexity.

📝 Problem & Approach

Given a positive integer rows, print a center-aligned full pyramid of * characters with rows lines.

// First 5 rows (spaces shown as ·)
// ····*
// ···***
// ··*****
// ·*******
// *********

Inputs & Outputs

Minimal workflow

for i from 1 to rows:
    for j from 1 to (rows - i):
        print " "
    for k from 1 to (2 * i - 1):
        print "*"
    print newline

Approach comparison

🔮 Live Preview

Choose a height between 1 and 14 and draw the centered pyramid in the browser.

Press "Draw pyramid".

Examples Gallery

Three complete C++ programs — nested space/star loops, console input, and a string() shortcut. Click View Output to reveal sample console results.

#include <iostream>
using namespace std;

int main() {
    int rows = 5;
    int i, j, k;

    for (i = 1; i <= rows; ++i) {
        for (j = 1; j <= rows - i; ++j) {
            cout << " ";
        }
        for (k = 1; k <= 2 * i - 1; ++k) {
            cout << "*";
        }
        cout << "\n";
    }

    return 0;
}

    *
   ***
  *****
 *******
*********

#include <iostream>
using namespace std;

int main() {
    int rows;
    int i, j, k;

    cout << "Enter the number of rows: ";
    cin >> rows;

    for (i = 1; i <= rows; ++i) {
        for (j = 1; j <= rows - i; ++j) {
            cout << " ";
        }
        for (k = 1; k <= 2 * i - 1; ++k) {
            cout << "*";
        }
        cout << "\n";
    }

    return 0;
}

Enter the number of rows: 4
   *
  ***
 *****
*******

#include <iostream>
#include <string>
using namespace std;

int main() {
    int rows = 5;

    for (int i = 1; i <= rows; ++i) {
        cout << string(rows - i, ' ') << string(2 * i - 1, '*') << "\n";
    }

    return 0;
}

    *
   ***
  *****
 *******
*********

🔎 Worked Walkthrough — rows = 4

Trace spaces, stars, and characters per row for each outer-loop value of i.

Star total: 1+3+5+7 = 16 = 4². Tip rows are shorter than the base — unlike Program 3’s fixed width.

🎯 Practice Problems

Try these variations to lock in the pattern.

Notes

⏱️ Time and Space Complexity

Total stars = rows²; each row also prints up to Θ(rows) spaces.

💡 Best Practices