CODEWITHSUNDEEP
pythonpython-3.xfor-loop
Caliman
Caliman

Reputation: 232

Drawing a right triangle (Python 3)

I'm having a bit of an issue. I'm trying to make this program output a right triangle based on the height and symbol that is specified by the user, but whenever I enter the symbol and height desired the program will output the correct shape, but upside-down. I've been having some difficulties getting a firm grasp of loops and through trial and error, this is the best I could come up with thus far. Could someone help a brother out, please. Thank yous in advance.

triangle_char = input('Enter a character:\n')
triangle_height = int(input('Enter triangle height:\n'))
print('')

for i in range (len(triangle_char)):
    for j in range (triangle_height):
        print((triangle_char) * triangle_height )
        triangle_height -= 1

This code will return this output when character is '*' and height is 5:

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

The expected output when those values are entered should be:

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

Upvotes: 0

Views: 27199

Answers (3)

sjjhsjjh
sjjhsjjh

Reputation: 333

Here it is as a script. I assumed that multiple input characters meant multiple output triangles. Also, that height:0 means zero lines in each triangle.

Tricky thing I learned today is that int("20.0") doesn't convert to 20; it raises an exception. The code works around that by converting to float first.

#!/usr/bin/python3

def triangles(characters, height):
    # We could call int(height) here except that int("20.0") for example raises
    # an error even though there is a pretty clear integer value. To get around
    # that, attempt to convert to float first.
    try:
        lines = float(height)
    except ValueError:
        # If we raise here, the error is like: cannot convert to float. That's
        # confusing, so we let it go.
        lines = height

    # If the value can't be converted to int, this raises an error like: cannot
    # convert to int. If it had already converted to float, this rounds down.
    lines = int(lines)

    for character in characters:
        # Loop will execute no times if lines==0, once if lines==1 and so on.
        for line in range(1, lines + 1):
            print(str(character) * line)
        print("")

if __name__ == '__main__':
    try:
        triangles(input("Enter characters: "), input("Enter height: "))
    except ValueError as error:
        print("Couldn't print triangles:", error)

Edit: Added sample output.

$ ./triangles.py 
Enter characters: jk
Enter height: 8
j
jj
jjj
jjjj
jjjjj
jjjjjj
jjjjjjj
jjjjjjjj

k
kk
kkk
kkkk
kkkkk
kkkkkk
kkkkkkk
kkkkkkkk

$ ./triangles.py 
Enter characters: .
Enter height: 3.0
.
..
...

$ ./triangles.py 
Enter characters: f
Enter height: 3.7
f
ff
fff

$ ./triangles.py 
Enter characters: duff
Enter height: duff
Couldn't print triangles: invalid literal for int() with base 10: 'duff'

Upvotes: 0

Axel
Axel

Reputation: 41

You can also do like this : 

triangle_char = input('Enter a character: ')
triangle_height = int(input('Enter triangle height: '))
print('')

j = 0;

while j <= triangle_height :
    print triangle_char * j
    j += 1

Upvotes: 0

Bruno9779
Bruno9779

Reputation: 1669

First your loops are both off; you are assigning values to i and j and not using them.

Second, the first loop is useless. If you input 3 characters it will repeat the block 3 times, but the variable triangle_height is decreased to 0 at the first pass, so nothing will be printed at the next iteration. Just remove this line

Third: You say that you need the triangle reversed, so, instead of decreasing triangle_height, use the value you assing to j in the for loop and forget about decreasing the variable. Since range starts counting from 0 you need to add 1 to it in the print statement:

triangle_char = input('Enter a character: ')
triangle_height = int(input('Enter triangle height: '))
print('')

for j in range (triangle_height):
    print((triangle_char) * (j + 1))

I have also replaced /n with a space in the input() methods because it looked pretty bad.

Upvotes: 2

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