Question

Just a simple question:

str = ['blah','blah']
for word in str:
    word = word * 2
print str

This just prints [‘blah’,’blah’]. Why (I know how to do this, just wondering why this isn’t allowed)?

Answer 1

The issue is that you have created a new string, but not updated the reference in the str list. This means that

word = word * 2

affects the variable word that has a new address, and this address (reference)
is not updated to the str list. to do that you need to:

str[i] = str[i] * 2

or

word = word * 2
str[i] = word