A Python star pattern is a script that prints * in rows. The outer for loop chooses the row. The inner loop prints each star with end="", then a bare print() ends that row.
"*" * n repeats the star n times, so print("*" * row) writes a solid row and the newline in one call. "*" + "*" is the string "**". "*" + 1 raises TypeError, because Python will not add a str and an int.
print ends the line unless you change end.print("*") writes one star and a newline. Pass end="" to stay on the row. A solid row can skip the inner loop and use "*" * row instead.
range(row) runs once per star. end="" keeps those stars on one line, and print() comes after that loop.
for row in range(1, rows + 1):
for col in range(row):
print("*", end="") # same row
print() # end the rowMap each part of the console shape to a Python value or call.
| Piece | Python | What it does |
|---|---|---|
| Star | print("*", end="") | Writes one star and stays on the row |
| Run of stars | "*" * n | A string of n stars |
| Indent | " " * n | n spaces |
| Join | "*" + "*" | The string "**" |
str + int | "*" + 1 | TypeError |
| New row | print() | Ends the row |
| Edge only | "*" if col in (0, width - 1) else " " | A hollow row |
Three scripts. Each one changes only the Python that chooses how many stars to print, and where the spaces go.
Row 1 prints one star. Each later row prints one more, because range(row) grows with the row.
rows = 5
for row in range(1, rows + 1):
for col in range(row):
print("*", end="")
print()range(1, rows + 1) walks the rows 1 through 5.end="" keeps the stars on one line.print() after the inner loop starts the next row."*" * rowCount down from 5. One print writes every star and the newline.
rows = 5
for row in range(rows, 0, -1):
print("*" * row)"*" * row builds the stars as one string.print writes that string and ends the row, so end="" is not needed.range(rows, 0, -1) makes each later line one star shorter and stops before 0.String addition puts the indent in front of an odd run of stars. One print writes the whole line.
rows = 5
for row in range(1, rows + 1):
spaces = " " * (rows - row)
stars = "*" * (2 * row - 1)
print(spaces + stars)+ joins two strings. It does not add a number to "*".print writes the joined line and ends the row.Each card is a full Python script: nested for loops, print("*", end="") or "*" * n, and print(). Open one for the walkthrough.
A full Python walkthrough of the right-angled star triangle, from print("*", end="") through print().
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