replacing a character in a string in python

Question

I am trying to replace a character in a string using python. I am using a function called find_chr to find the location of the character that needs to be replaced.

def main():
 s='IS GOING GO'
 x='N'
 y='a'
 rep_chr(s,x,y)
def find_chr(s,char):
 i=0
 for ch in s:
 if ch==char:
 return (i)
 break 
 i+=1
 return -1
def rep_chr(s1,s2,s3):
 return print(s1==s1[0:find_chr(s1,s2)]+s3+s1[(find_chr(s1,s2)+1):])
main()

My problem is that instead of getting the new string, the function is returning 'False'. I would appreciate any pointer to get the replaced string.

• Mr. Polywhirl: Looks like you changed print(rep_chr(s,x,y)) to (rep_chr(s,x,y))...
• Hugh Bothwell: Why are you not using str.replace? Just trying to recreate it for fun?

Answer 1

change

return print(s1==s1[0:find_chr(s1,s2)]+s3+s1[(find_chr(s1,s2)+1):])

to

return s1[0:find_chr(s1,s2)]+s3+s1[(find_chr(s1,s2)+1):]

and print the result in your main:

print(rep_chr(s,x,y))

Answer 2

There is an inbuilt function:

string.replace(old, new, count)

this returns a modified copy

count is optional and is the number of times to replace - if it is set to 2 it will replace the first two occurrences.

string = 'abc abc abc def'
string.replace('abc','xyz',2)

returns

'xyz xyz abc def'

Answer 3

The problem is in your print statement inside rep_chr function.

s1==s1[0:find_chr(s1,s2)]+s3+s1[(find_chr(s1,s2)+1):]

The above statement means is s1 equal to s1[0:find_chr(s1,s2)]+s3+s1[(find_chr(s1,s2)+1):]? which is false and that's why you are getting False as output.