Removing a character from a string

Question

I am asked the following:

def myRemove( str, ch ):
 # Return a new string with the first occurrence of ch removed. If there is none, return str.

Sample run

>>> myRemove( "abcdabcd", "a")
'bcdabcd'
>>> myRemove( "abcdabcd", "x")
'abcdabcd'
>>> myRemove( "abcdabcd", "d")
'abcabcd'

I have tried a few different methods but have not been able to figure the problem out. Here is my attempt:

def myRemove( str, ch ):
 for num in range (0, len(str)):
 if (str[num] == ch):
 return str[0:num] + str[num + 1:]
 else:
 return str

There is also an extension to this problem which asks : Return a new string with all occurrences of ch removed. If there are none, return str. However, since I have not been able to solve the first part, naturally I was not sure how to solve the second. Would appreciate any guidance.

• Yuval Filmus: This is a question about elementary programming, which is not quite on-topic here.

Answer 1

Notice that the loop will only occur once! In the beginning num will be 0. At this point, we enter the if statement:

• if we got that str[0] == ch (notice that num==0 and thus str[0]==str[num]), then we return some string
• otherwise we return another string

The important thing here, is that no matter what - we will quit in the first iteration of the for loop.

To fix this, consider placing the return str outside the for loop (without else as well)

• Obsessive Integer: Is it possible for me to make simple modifications which return a new string with all occurrences of ch removed? Or should I should I try to create a while loop?
• nir shahar: There is a (quite simple) modification you can do. Try to think how not to stop only at the first character you see.