How do I modify a single character in a string, in Python? Something like:
a = "hello"
a[2] = "m"
'str' object does not support item assignment.
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possible duplicate of [Change one character in a string in Python?](http://stackoverflow.com/questions/1228299/change-one-character-in-a-string-in-python) – Wolf Mar 02 '15 at 13:54
4 Answers
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Strings are immutable in Python. You can use a list of characters instead:
a = list("hello")
When you want to display the result use ''.join(a):
a[2] = 'm'
print ''.join(a)
Mark Byers
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In python, string are immutable. If you want to change a single character, you'll have to use slicing:
a = "hello"
a = a[:2] + "m" + a[3:]
JoshD
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1I suppose this would cost more memory if it's a really big string since you have to join three other strings together to form a new string, right? – Shane Oct 05 '10 at 05:27
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Oh, yeah! If you need to do a whole bunch of these type of manipulations, it's best to use a list of characters. Unless you happen to already have a string and just happen to want to change one character. Even then, it's probably faster to create and modify a list. – JoshD Oct 05 '10 at 05:29
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8
Try constructing a list from it. When you pass an iterable into a list constructor, it will turn it into a list (this is a bit of an oversimplification, but usually works).
a = list("hello")
a[2] = m
You can then join it back up with ''.join(a).
detly
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