9.7. Strings are Immutable¶
One final thing that makes strings different from some other Python
collection types is that you are not allowed to modify the individual
characters in the collection. It is tempting to use the []
operator on the left side of an assignment, with the intention of
changing a character in a string. For example, in the following code,
we would like to change the first letter of greeting.
1
greeting: str2
greeting = "Hello, world!"3
greeting[0] = 'J' # ERROR!4
print(greeting)5
(cg08_imm1)
Instead of producing the output Jello, world!, this code produces
the runtime error TypeError: 'str' object does not support item
assignment.
Check your understanding
strings-9-1: What is printed by the following statements:
s: str
s = "Ball"
s[0] = "C"
print(s)
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