How to delete a character from a string using Python
There is a string, for example.
How can I remove the middle character, i.e.,
M from it? I don't need the code. I want to know:
- Do strings in Python end in any special character?
- Which is a better way - shifting everything right to left starting from the middle character OR creation of a new string and not copying the middle character?
In Python, strings are immutable, so you have to create a new string. You have a few options of how to create the new string. If you want to remove the 'M' wherever it appears:
newstr = oldstr.replace("M", "")
If you want to remove the central character:
midlen = len(oldstr)/2 # //2 in python 3 newstr = oldstr[:midlen] + oldstr[midlen+1:]
You asked if strings end with a special character. No, you are thinking like a C programmer. In Python, strings are stored with their length, so any byte value, including
\0, can appear in a string.
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This is probably the best way:
original = "EXAMPLE" removed = original.replace("M", "")
Don't worry about shifting characters and such. Most Python code takes place on a much higher level of abstraction.
To replace a specific position:
s = s[:pos] + s[(pos+1):]
To replace a specific character:
s = s.replace('M','')
Strings are immutable. But you can convert them to a list, which is mutable, and then convert the list back to a string after you've changed it.
s = "this is a string" l = list(s) # convert to list l = "" # "delete" letter h (the item actually still exists but is empty) l[1:2] =  # really delete letter h (the item is actually removed from the list) del(l) # another way to delete it p = l.index("a") # find position of the letter "a" del(l[p]) # delete it s = "".join(l) # convert back to string
You can also create a new string, as others have shown, by taking everything except the character you want from the existing string.
How can I remove the middle character, i.e., M from it?
You can't, because strings in Python are immutable.
Do strings in Python end in any special character?
No. They are similar to lists of characters; the length of the list defines the length of the string, and no character acts as a terminator.
Which is a better way - shifting everything right to left starting from the middle character OR creation of a new string and not copying the middle character?
You cannot modify the existing string, so you must create a new one containing everything except the middle character.