CODEWITHSUNDEEP
python
Ask and Learn
Ask and Learn

Reputation: 8959

Python syntax error when I use if on same line

I must be doing something stupid but I just don't see it. I could not get the following simple code to work.

>>> def a_bigger_than_b(a,b):
...   'Yes' if a > b
  File "<stdin>", line 2
    'Yes' if a > b
                 ^
SyntaxError: invalid syntax

Upvotes: 0

Views: 163

Answers (3)

sundar nataraj
sundar nataraj

Reputation: 8692

def a_bigger_than_b(a,b):
...   return 'Yes' if a > b else 'No!'

Actually your using it as Ternary Operator in such case you need else

i think you must give else this can be well understood by

first 

c='Yes' if a > b

what will be the value for a if a is smaller than b this case is ambiguous so else is must

correct syntax

c='Yes' if a > b else 'No!'

A detailed explanation was given by here

*On 9/29/2005, Guido decided to add conditional expressions in the
    form of "X if C else Y".

    The motivating use case was the prevalance of error-prone attempts
    to achieve the same effect using "and" and "or".

    Previous community efforts to add a conditional expression were
    stymied by a lack of consensus on the best syntax.  That issue was
    resolved by simply deferring to a BDFL best judgment call.*

Upvotes: 4

glglgl
glglgl

Reputation: 91017

Your syntax resembles me a bit of Perl.

I am not sure what exactly you want

def a_bigger_than_b(a,b):
    'Yes' if a > b

to do; there are several possimble interpretations.

Amongst the ones already mentioned, you could as well want

def a_bigger_than_b(a, b):
    if a > b: return 'Yes'

which does nothing in the <= case and eventually reaches the end of the function, where (implicitly) None is returned.

This is the one-liner syntax for Python, quite equvalent to the do_whatever if foo syntax in Perl.

Be aware that a function must always return a value; if you don't explicitly, None is returned implicitly.

Upvotes: 2

pancakes
pancakes

Reputation: 712

You may change if statement in simpler one:

def a_bigger_than_b(a, b):
    return a > b and 'Yes'

Upvotes: 1

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