Making triangles in Python

Question

Below is a code I made in Python for our lab activity which makes a triangle.

side = input("Input side: ")

def triangle(x):
    print ((x - 1)*" "),"*"
    asterisk = "*"
    space = side
    for i in range(x):
            asterisk = "**" + asterisk
            space = (space-1) * " "
            print space,asterisk

triangle(side)

The output should be this:

  *
 ***
*****

I got the number of asterisks on each row correctly, but I cannot figure out how to make the necessary amount of spaces to make it look like a triangle. Using the above code, which I think might be the solution, always produces an error at line 9. Any help I appreciated. (I'm new here so if I violated some rules please let me know.) Thanks and good day!

You get error at line 9 because you are using Python3 ,and the line needs to be: `print(space,asterisk)` — HaR, Sep 18 '18 at 10:13
@HaR I'm using Python 2.7.13. The error is "TypeError: unsupported operand type(s) for -: 'str' and 'int'". I — Stick1000, Sep 18 '18 at 10:17
@Stick1000 better not saying you got an error. Instead show the error, please (as an edit in your question). And also you mixed 4 spaces with 8 spaces indendation, see [editing-help](https://stackoverflow.com/editing-help). -- `space` or `side` is a string which needs to be converted to int. — colidyre, Sep 18 '18 at 10:17
If you are learning Python in 2018, you should definitely be targeting the currently recommended and supported version of the language, which is Python 3. Version 2 was originally slated to be end-of-lifed already, although it got a couple of miserable extra years in terminal care. — tripleee, Sep 18 '18 at 10:23
I rolled back your latest edit (it's still available from the [revision history](https://stackoverflow.com/posts/52384142/revisions)). Your question should remain strictly a question, though you are more than welcome to post an answer of your own. — tripleee, Sep 18 '18 at 10:25

Vineeth Sai · Accepted Answer · 2018-09-18T10:27:07.047

You are getting the error(TypeError) because you are assigning the space variable with a string type, and then you are subtracting it in the next loop. Edited code would look like this (In python 2.7) and Never mix 4 spaces and 8 spaces indentation.

side = input("Input side: ")

def triangle(x):
    print ((x)*" "),"*"
    asterisk = "*"
    spaces = side
    for i in range(x):
        asterisk = "**" + asterisk
        spaces -= 1
        print ' ' * spaces,
        print asterisk 

triangle(side)

score 0 · Answer 2 · answered Sep 18 '18 at 10:27

0

I write a new one in python3.5,And it may be suit for you.But it is not prefect

side = 4

def triangle(x):
    for y in range(1,x):
        s = 2*y - 1
        b = x - y
        print(" "*b+"*"*s)
triangle(side)

Output:

   *
  ***
 *****

answered Sep 18 '18 at 10:27

KC.

2,981
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score 0 · Answer 3 · edited Nov 20 '21 at 17:21

0

Here is the code to have an isosceles triangle:

def print_triangle(n):
    for i in range(1, n+1):
        print (" "*(n-i), end=" ")
        print (("*"*i)+(i*"*"))

print(print_triangle(6))

Output:

      **
     ****
    ******
   ********
  **********
 ************
None

edited Nov 20 '21 at 17:21

tdy

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answered Nov 20 '21 at 01:01

Nick Mbunte

1

see [why is this printing "None" in the output?](https://stackoverflow.com/q/28812851/13138364) for why your code includes "None" in the output – tdy Nov 20 '21 at 17:23

Making triangles in Python

3 Answers3