Program to print half Diamond star pattern

Last Updated : 27 Oct, 2026

Given an integer n, the task is to print half-diamond-star pattern.

Examples:

Input: n = 3
Output:
*
**
***
**
*

Input: n = 6
Output:
*
**
***
****
*****
******
*****
****
***
**
*

Nested Loops -O(n^2) Time and O(1) Space

The pattern can be divided into two parts: the upper half and the lower half. We can print each half separately using loops.

  • Upper half: Print stars in increasing order. The first row contains 1 star, the second row contains 2 stars, and so on. Therefore, the ith row contains i stars.
  • Lower half: Print stars in decreasing order. Each row contains one star fewer than the previous row. Therefore, the ith row contains n - i stars.
C++ 
using namespace std;

// Function to print the
// half diamond star pattern
void halfDiamondStar(int n)
{
    int i, j;

    // Loop to print the upper half
    // diamond pattern
    for (i = 0; i < n; i++) {
        for (j = 0; j < i + 1; j++)
            cout << "*";
        cout << "\n";
    }

    // Loop to print the lower half
    // diamond pattern
    for (i = 1; i < n; i++) {
        for (j = i; j < n; j++)
            cout << "*";
        cout << "\n";
    }
}

// Driver Code
int main()
{
    int n = 5;

    // Function Call
    halfDiamondStar(n);
}
Java 
class GFG{

// Function to print the
// half diamond star pattern
static void halfDiamondStar(int n)
{
    int i, j;

    // Loop to print the upper half
    // diamond pattern
    for (i = 0; i < n; i++)
    {
        for (j = 0; j < i + 1; j++)
            System.out.print("*");
        System.out.print("\n");
    }

    // Loop to print the lower half
    // diamond pattern
    for (i = 1; i < n; i++)
    {
        for (j = i; j < n; j++)
            System.out.print("*");
        System.out.print("\n");
    }
}

// Driver Code
public static void main(String[] args)
{
    int n = 5;

    // Function Call
    halfDiamondStar(n);
}
}

// This code is contributed by Rohit_ranjan
Python 
def halfDiamondStar(n):
    
    # Loop to print the upper half
    # diamond pattern
    for i in range(n):
        
        for j in range(0, i + 1):
            print("*", end = "")
        print()
    
    # Loop to print the lower half
    # diamond pattern
    for i in range(1, n):
        
        for j in range(i, n):
            print("*", end = "")
        print()

# Driver Code
n = 5

# Function Call
halfDiamondStar(n)
C# 
using System;

class GFG{

// Function to print the
// half diamond star pattern
static void halfDiamondStar(int n)
{
    int i, j;

    // Loop to print the upper half
    // diamond pattern
    for(i = 0; i < n; i++)
    {
    for(j = 0; j < i + 1; j++)
        Console.Write("*");
    Console.Write("\n");
    }

    // Loop to print the lower half
    // diamond pattern
    for(i = 1; i < n; i++)
    {
    for(j = i; j < n; j++)
        Console.Write("*");
    Console.Write("\n");
    }
}

// Driver Code
public static void Main(String[] args)
{
    int n = 5;

    // Function Call
    halfDiamondStar(n);
}
}

// This code is contributed by Rohit_ranjan
JavaScript 
// Function to print the
// half diamond star pattern
function halfdiamondstar(n)
{
    let i, j;

    // Loop to print the upper half
    // diamond pattern
    for (i = 0; i < n; i++) {
        for (j = 0; j < i + 1; j++)
            process.stdout.write("*");
        console.log();
    }

    // Loop to print the lower half
    // diamond pattern
    for (i = 1; i < n; i++) {
        for (j = i; j < n; j++)
            process.stdout.write("*");
        console.log();
    }
}


// driver code
let n = 5;

// Function Call
halfdiamondstar(n);

Output
*
**
***
****
*****
****
***
**
*
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