Python def function How do you specify the end of the function

Question

I m just learning python and confused when a  def  of a function ends   I see code samples like   def myfunc a 4 b 6       sum   a   b     return sum  myfunc     I know it doesn t end because of the return  because I ve seen if statements    if FOO than return BAR  else return FOOBAR    How does Python know this isn t a recursive function that calls itself   When the function runs does it just keep going through the program until it finds a return   That d lead to some interesting errors   Thanks

User · Answer

Interestingly  if you re just typing at the python interactive interpreter  you have to follow a function with a blank line   This does not work   def foo x     return x 1 print  last    although it is perfectly legal python syntax in a file   There are other syntactic differences when typing to the interpreter too  so beware

User · Answer

So its the indentation that matters   As other users here have pointed out to you  when the indentation level is at the same point as the def function declaration your function has ended   Keep in mind that you cannot mix tabs and spaces in Python   Most editors provide support for this

User · Answer

Python is white-space sensitive in regard to the indentation  Once the indentation level falls back to the level at which the function is defined  the function has ended

User · Answer

white spaces matter  when block is finished  that s when the function definition is finished   when function runs  it keeps going until it finishes  or until return or yield statement is encountered  If function finishes without encountering return or yield statements None is returned implicitly   there is plenty more information in the tutorial

User · Answer

It uses indentation   def func         funcbody      if cond            ifbody      outofif   outof func

User · Answer

In Python whitespace is significant  The function ends when the indentation becomes smaller  less    def f        pass   first line     pass   second line pass    lt -- less indentation  not part of function f    Note that one-line functions can be written without indentation  on one line   def f    pass   And  then there is the use of semi-colons  but this is not recommended   def f    pass  pass   The three forms above show how the end of a function is defined syntactically  As for the semantics  in Python there are three ways to exit a function    Using the return statement  This works the same as in any other imperative programming language you may know  Using the yield statement  This means that the function is a generator  Explaining its semantics is beyond the scope of this answer  Have a look at Can somebody explain me the python yield statement  By simply executing the last statement  If there are no more statements and the last statement is not a return statement  then the function exists as if the last statement were return None  That is to say  without an explicit return statement a function returns None  This function returns None   def f        pass   And so does this one   def f        42

User · Answer

In my opinion  it s better to explicitly mark the end of the function by comment  def func           funcbody         end of subroutine func      The point is that some subroutine is very long and is not convenient to scroll up the editor to check for which function is ended  In addition  if you use Sublime  you can right click -  Goto Definition and it will automatically jump to the subroutine declaration

User · Answer

To be precise  a block ends when it encounter a non-empty line indented at most the same level with the start  This non empty line is not part of that block For example  the following print ends two blocks at the same time   def foo        if bar          print  bar   print  baz    ends the if and foo at the same time   The indentation level is less-than-or-equal to both the def and the if  hence it ends them both   Lines with no statement  no matter the indentation  does not matter  def foo        print  The line below has no indentation       print  Still part of foo    But the statement that marks the end of the block must be indented at the same level as any existing indentation  The following  then  is an error   def foo        print  Still correct     print  Error because there is no block at this indentation    Generally  if you re used to curly braces language  just indent the code like them and you ll be fine   BTW  the  standard  way of indenting is with spaces only  but of course tab only is possible  but please don t mix them both

[python] Python def function: How do you specify the end of the function?

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