how can i replace character in a string?

November 24, 2021

hi i’m trying to simulate what the user might type for one word i.e hello so basically I have it printed out to the terminal _ _ _ _ _ and I want to replace the "_" with lets say "l" and match where it is in the string,here is my code

import re
str1="hello"
lettercheck="l"
a=re.search(lettercheck,str1)
span=(a.span())
print(span)
print(str1[span[0])
count=0
ab="_"
for char in str1:
    print(ab,end=" ")
    if lettercheck==char
    count +=1
    replacechar=str1.replace(ab,str1[span[0]])
    print(replacechar)

which prints out
_ _ _ hello
_ hello
_
can anyone explain where I went wrong here and what can I do to fix it? note the count is just for how times how to time the letter recurrences which i will work on later on my code this is just an example to try to understand what is going on

>Solution :

All of the searching and replacing can be simplified. The regex library is not needed here:

str1 = 'hello'
lettercheck = "l"

positions = [pos for pos, char in enumerate(str1) if char == lettercheck]

for i in range(len(str1)):
    if i in positions:
        print(lettercheck, end='')
    else:
        print('_', end='')

returns: