Python Program to Print Hourglass Star Pattern

Introduction

An hourglass star pattern consists of stars arranged in the shape of an hourglass. It has two parts: an inverted pyramid followed by a regular pyramid. This pattern is a great way to practice using loops to control the number of stars and spaces in a visually appealing way.

Problem Statement

Create a Python program that:

• Accepts the number of rows for the hourglass pattern.
• Prints an hourglass-shaped pattern using stars (*).

Example:

• Input: rows = 5
• Output:

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

Solution Steps

1. Input the Number of Rows: The user specifies the number of rows for the upper part of the hourglass (the inverted pyramid).
2. Use Nested Loops: The outer loops handle the rows, and the inner loops handle printing the stars and spaces for both the inverted pyramid (upper part) and the regular pyramid (lower part).
3. Display the Hourglass Pattern: Print stars in decreasing order for the upper part and increasing order for the lower part, with spaces for alignment.

Python Program

# Step 1: Input the number of rows for the hourglass pattern
rows = int(input("Enter the number of rows: "))

# Step 2: Print the upper part of the hourglass (inverted pyramid)
for i in range(rows, 0, -1):
    # Print leading spaces for alignment
    print(" " * (rows - i), end="")
    
    # Print stars for the current row
    print("*" * (2 * i - 1))

# Step 3: Print the lower part of the hourglass (regular pyramid)
for i in range(2, rows + 1):
    # Print leading spaces for alignment
    print(" " * (rows - i), end="")
    
    # Print stars for the current row
    print("*" * (2 * i - 1))

Explanation

Step 1: Input the Number of Rows

• The program begins by asking the user to input the number of rows for the hourglass pattern. This value will determine the height of the hourglass.

Step 2: Print the Upper Part of the Hourglass (Inverted Pyramid)

• The first loop handles the rows for the inverted pyramid, starting from rows and decreasing to 1.
  • The first inner part prints spaces to align the stars correctly, shifting them to the center.
  • The second inner part prints stars (*) in decreasing order. The number of stars for each row is calculated as 2 * i - 1.

Step 3: Print the Lower Part of the Hourglass (Regular Pyramid)

• The second loop handles the rows for the regular pyramid, starting from 2 and increasing to rows.
  • The same logic as the inverted pyramid is applied but in reverse order, to form the lower part of the hourglass.

Output Example

For rows = 5, the output will be:

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

For rows = 4, the output will be:

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

Conclusion

This Python program prints an hourglass star pattern using nested loops to create both an inverted and a regular pyramid. Stars are printed with spaces for alignment, forming the hourglass shape. This exercise helps in practicing loop control, alignment, and output formatting in Python.