CODEWITHSUNDEEP
python-3.xvariables
Lotexiu
Lotexiu

Reputation: 1

Any way to change variable within another variable that is being changed?

I need to change the value of nValor on the same line that I'm messing with cInText

the desired way of doing:

cText = "Something"
nValor = len(cText)-1
cInText = ""
while nValor >= 0:
    cInText += cText[nValor -= 1]
print(cInText)

the unwanted way of doing:

cText = "Something"
nValor = len(cText)-1
cInText = ""
while nValor >= 0:
    cInTexto += cTexto[nValor]
    nValor -= 1
print(cInTexto)

Upvotes: 0

Views: 45

Answers (1)

YurkoFlisk
YurkoFlisk

Reputation: 1055

Judging by your second excerpt it seems you ideally want post-decrement operator behaviour, but Python has neither pre- nor post-increment/decrement operators. See this question and answers for details.

You can, however, get desired behaviour by using multiple-target assignment like this:

cInText, nValor = cInText + cText[nValor], nValor - 1

First, right-hand side will be evaluated to a tuple of 2 elements, after which 2 comma-separated targets will be assigned to respective tuple elements.

If you want pre-decrement behaviour however (as suggested by your first example), since Python 3.8 you can use assignment expression (walrus assignment) like this:

cInText += cText[nValor := nValor - 1]

Here, value of expression nValor := nValor - 1 is just nValor - 1, but as a side-effect this expression also assigns this value to nValor, as desired.

Note that in your case post-decrement behaviour is needed if you want to reverse cInText (otherwise, nValor indexes will be incorrect and result in negative index on the last iteration). Also, if this is not a toy example and your original problem is to do a reverse, take a look at this question and answers.

Upvotes: 1

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