CODEWITHSUNDEEP
python
aWebDeveloper
aWebDeveloper

Reputation: 38392

Brackets around if and for

I am a python newbie and have a question. Why can a if allow a brackets and not for.

  1. if (1==2):

  2. for (i in range(1,10)):

  3. while (i<10):

First one and third one are valid syntax but not second one.

File "<stdin>", line 2
    for (i in range(1,10)):
                          ^

Upvotes: 4

Views: 356

Answers (2)

TerryA
TerryA

Reputation: 60004

Because for (i in range(1,10)) isn't syntactically correct.

Lets assume (i in range(1,10)) was parsed anyway, it would return a boolean. So then you're trying to say for True or for False, and booleans can't be iterated, and it's invalid syntax.

The reason why your other examples work is because they expect a boolean, which is what is returned from 1 == 2 and i < 10

Upvotes: 7

Ciro Santilli OurBigBook.com
Ciro Santilli OurBigBook.com

Reputation: 383846

  • if expects a value (True of False). You can put parenthesis around any values: (1) + (1)

  • for VAR in LIST is a fixed syntax which does not expect a value single value, but rather two inputs:

    • a variable name
    • what you will iterate over

    So why would the Python language allow extra parenthesis there?

As someone had pointed on a now deleted answer (why?), this is the syntax for the for statement: http://docs.python.org/3/reference/compound_stmts.html#the-for-statement :

for_stmt ::=  "for" target_list "in" expression_list ":" suite
              ["else" ":" suite]

Upvotes: 1

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