The good/old control statements – if

if statement has 3 keywords only and a straightforward syntax:

if <cond-1>:
     <stat-1>
elif <cond-2>:
     <stat-2>
else:      <stat-n>

Conditions seem to be ending with ':'. 'else' is a condition also here – "otherwise". like default of switch.


Letting the following equally work:

if x < 0: x = 0; print('Negative changed to zero')
elif x == 0: print('Zero')
elif x == 1: print('Single')
else: print('More')

as well as

if x < 0:
     x = 0
     print('Negative changed to zero')
elif x == 0:
     print('Zero')
elif x == 1:
     print('Single')
else:
     print('More')

Note ';' as line separators between same-level/inner statements. So – `;` and line-separator seem to be  equivalent at such use (?) Mental note - see whether this is accurate, and can generalize this to their other/all use.

The following is an error thou. Looks like merely the syntax of if-statement and nothing else:

if x < 0: x = 0; print('Negative changed to zero') else: print('More')

Neither is the following – ';' isn't a substitute for line separator here:

if x < 0: x = 0; print('Negative changed to zero'); else: print('More')

The way it seems, ';' stands for line separator only in between the statements of the same inner-most code block. (?)

The source i look up for this article was https://docs.python.org/3/tutorial/controlflow.html#if-statements.

Comments

Post a Comment

Popular posts from this blog

Indentation!

Discovered indentation/errors of Python. Knew it – but, not having used it, hadn't encountered it. I'm sure there's a way to simply handling them. But frustrating still. Kind of makes you loose respect to the language. what it does depends on where/which column you type. not what you type. 
Read more

Python - what for?

I liked what this blog said re. the motivation ("1. Figure out what motivates you" section about 1/5th of the page): Data science / Machine learning Mobile apps Websites Games Hardware / Sensors / Robots Scripts to automate your work Mine is – Data science / Machine learning , and that's about it. And Scripts to automate your work , but that comes as a by-product. I've got other technologies in tact for those others. Python is algorithms to me. Not sure how comprehensive the above list is (neither does the author himself - says ".., such as"), but suits me – serves the purpose. Lays out a view.  
Read more

for loop and slice

for statement iterates on any discrete sequence of items – as in Java. The syntax is simple: f or <variable > in <sequence> :     <statement> Eg.: words = [ ' this ' , ' that ' , ' another ' ] for w in words:      print (w, len(w)) Side-note here –       for w in words[:]: print (w)    has the same effect as      print (words) You can update a list within the for loop – unlike Java. for w in words:      if len(w) > 6 :           words. remove (w) But, better use a slice to end up with the expected effect in some cases. For instance, the following is an infinite for-loop: for w in words:      if len(w) > 6 :           print (w, ' her...
Read more