String triangle pattern does not print the correct output (when the string contains more than one wo-CodePudding

Trying to create a triangular print pattern for an input string caused the following problem. Here is the code:

string=input("Please enter your word: ")
printable=""

l=0
while l<len(string):
    for i in string:
        printable =i
        print(printable)
        l =1

q=0
while q!=len(string):
    for z in string:
        string=string.replace(string[-1],"")
        if string=="":
            break
        print(string)

For an input containing only one word ("Python") it works fine and it prints out:

P
Py
Pyt
Pyth
Pytho
Python
Pytho
Pyth
Pyt
Py
P

The problem starts when a string with a space between the words is entered ("Elvis Presley"):

E
El
Elv
Elvi
Elvis
Elvis 
Elvis P
Elvis Pr
Elvis Pre
Elvis Pres
Elvis Presl
Elvis Presle
Elvis Presley
Elvis Presle
Elvis Prsl
Evis Prs
Evi Pr
Evi P
Evi 
Evi
Ev
E

Most probably it is because when it reaches back Pres"l" it also removes the "l" in Elvis. How can I fix that? Would be glad if you assist me. Thank you!

CodePudding user response：

This has nothing to do with multiple words, the problem is when there are duplicate characters in the string. string.replace(string[-1],"") will remove all the occurrences of the last character. So when the last character is l, it removes the l in Elvis as well.

Use a slice to remove the last character, not replace().

string = string[:-1]

CodePudding user response：

Actually it doesn't work with a single word string, too. if I enter "Banana" the output is:

B
Ba
Ban
Bana
Banan
Banana
Bnn
B

When the program reaches a repeating character it is being removed from everywhere.

CodePudding user response：

The problem is in your second loop string=string.replace(string[-1],""). If you replace the last character of string you replace all instances. So that 'Elvis Presle'.replace('e', '') results in "Elvis Prsl".

Instead of replace use indexing - string = string[:-1].

P.S. You can simplify looping through string like this:

while string:
    string = string[:-1]
    print(string)

CodePudding user response：

The problem is on

string=string.replace(string[-1],"")

It replace letters with nothing so when letter 'e' was found all of them are erased same as letter 'l'. You can use indexing instead of letters.

l=0
while l<len(string) 1:

    print(string[:l])
    l =1

It means that take letter by letter starting from the left to the right. Then you can use reverse of the slicing method. string[:-1] means that take until to the last letter.

l=1
while l<len(string) 1:

    print(string[:l*-1])
    l =1

Thus the entire code will be:

string=input("Please enter your word: ")

l=0
while l<len(string) 1:

    print(string[:l])
    l =1

l=1
while l<len(string) 1:

    print(string[:l*-1])
    l =1