Why is semicolon allowed in this python snippet

Question

Python does not warrant the use of semicolons to end statements  So why is this  below  allowed   import pdb  pdb set trace

User · Answer

It s allowed because authors decided to allow it  https   docs python org 2 reference simple stmts html  If move to question why authors decided todo so  I guess it s so because semi-column is allowed as simple statement termination at least in the following langages  C    C  C   R  Matlab Perl      So it s faster to move into usage of Python for people with background in other language  And there are no lose of generality in such deicison

User · Answer

Semicolons are part of valid syntax  8  Compound statements  The Python Language Reference

User · Answer

Python does not require semi-colons to terminate statements   Semi colons can be used to delimit statements if you wish to put multiple statements on the same line   Now  why is this allowed   It s a simple design decision   I don t think Python needs this semi-colon thing  but somebody thought it would be nice to have and added it to the language

User · Answer

Semicolons can be used to one line two or more commands  They don t have to be used  but they aren t restricted      The semicolon       allows multiple statements on the single line given that neither statement starts a new code block    http   www tutorialspoint com python python basic syntax htm

User · Answer

Multiple statements on one line may include semicolons as separators  For example  http   docs python org reference compound stmts html In your case  it makes for an easy insertion of a point to break into the debugger   Also  as mentioned by Mark Lutz in the Learning Python Book  it is technically legal  although unnecessary and annoying  to terminate all your statements with semicolons

User · Answer

Semicolon       is only needed for separation of statements within a same block  such as if we have the following C code   if a gt b    largest a     here largest and count are integer variables count  1      It can be written in Python in either of the two forms   if a gt b         largest a     count count 1   Or  if a gt b     largest a count count 1   In the above example you could have any number of statements within an if block and can be separated by     instead   Hope that nothing is as simple as above explanation

User · Answer

Semicolon in the interpreter  Having read the answers  I still miss one important aspect of using semicolons  possibly the only one where it really makes a difference     When you re working in an interpreter REPL  the Python interactive shell  IDLE  ipython  the value of the last expression is printed to the screen and usually this is the intended behavior   Using an expression for side effects  But in some cases you want to evaluate an expression for its side effects only  e g   to see the results of your simulation plotted by matplotlib   In this cases you  probably  don t want to see the screenful of reprs of matplotlib objects that are sometimes returned by a call to a matplotlib function and  in IPython at least   one of the possibilities you have is to append a semicolon to the overly verbose statement  now IPython sees  the input line as composed by two expressions  the matplotlib invocation and a null statement  so that the value of the compound expression is None and nothing is printed to the screen by the interpreter   the other possibility being assignment  as in     plot      but I find that a bit more intrusive    Personal remark  IMHO  the use of the semicolon to suppress not desired output in the interpreter has become more relevant following the introduction of the IPyton notebook  that permits to save the input and the output  including graphical output  of an interpreter session for documentation and eventual reuse

User · Answer

A quote from  When Pythons Attack      Don t terminate all of your statements with a semicolon  It s technically legal to do this in Python  but is totally useless unless you re placing more than one statement on a single line  e g   x 1  y 2  z 3

User · Answer

Python does let you use a semi-colon to denote the end of a statement if you are including more than one statement on a line

User · Answer

As everyone else has noted  you can use semicolons to separate statements  You don t have to  and it s not the usual style   As for why this is useful  some people like to put two or more really trivial short statements on a single line  personally I think this turns several trivial easily skimmed lines into one complex-looking line and makes it harder to see that it s trivial    But it s almost a requirement when you re invoking Python one liners from the shell using python -c   lt some python code gt    Here you can t use indentation to separate statements  so if your one-liner is really a two-liner  you ll need to use a semicolon  And if you want to use other arguments in your one-liner  you ll have to import sys to get at sys argv  which requires a separate import statement  e g   python -c  import sys  print     join sorted sys argv 1      5 2 3 1 4 1 2 3 4 5

User · Answer

Semicolons  like dots  commas and parentheses  tend to cause religious wars  Still  they  or some similar symbol  are useful in any programming language for various reasons    Practical  the ability to put several short commands that belong conceptually together on the same line   A program text that looks like a narrow snake has the opposite effect of what is intended by newlines and indentation  which is highlighting structure  Conceptual  separation of concerns between pure syntax  in this case  for a sequence of commands  from presentation  e g  newline   in the old days called  pretty-printing     Observation  for highlighting structure  indentation could be augmented replaced by vertical lines in the obvious way  serving as a  visual ruler  to see where an indentation begins and ends   Different colors  e g  following the color code for resistors  may compensate for crowding

User · Answer

http   docs python org reference compound stmts html     Compound statements consist of one or more    clauses     A clause   consists of a header and a    suite     The clause headers of a particular   compound statement are all at the same indentation level  Each clause   header begins with a uniquely identifying keyword and ends with a   colon  A suite is a group of statements controlled by a clause  A   suite can be one or more semicolon-separated simple statements on the   same line as the header  following the header   s colon  or it can be   one or more indented statements on subsequent lines  Only the latter   form of suite can contain nested compound statements  the following is   illegal  mostly because it wouldn   t be clear to which if clause a   following else clause would belong   if test1  if test2  print x       Also note that the semicolon binds tighter than the colon in this   context  so that in the following example  either all or none of the   print statements are executed   if x  lt  y  lt  z  print x  print y  print z     Summarizing   compound stmt      if stmt                      while stmt                      for stmt                      try stmt                      with stmt                      funcdef                      classdef                      decorated suite              stmt list NEWLINE   NEWLINE INDENT statement  DEDENT statement          stmt list NEWLINE   compound stmt stmt list          simple stmt      simple stmt

User · Answer

I realize I am biased as an old C programmer  but there are times when the various Python conventions make things hard to follow   I find the indent convention a bit of an annoyance at times     Sometimes  clarity of when a statement or block ends is very useful   Standard C code will often read something like this   for i 0  i lt 100  i          do something here      do another thing here     continue doing things    where you use the whitespace for a lot of clarity - and it is easy to see where the loop ends   Python does let you terminate with an  optional  semicolon   As noted above  that does NOT mean that there is a statement to execute followed by a  null  statement   SO  for example   print x   print y     Is the same as   print x  print y    If you believe that the first one has a null statement at the end of each line  try - as suggested - doing this   print x      It will throw a syntax error     Personally  I find the semicolon to make code more readable when you have lots of nesting and functions with many arguments and or long-named args   So  to my eye  this is a lot clearer than other choices   if some boolean is true      call function          long named arg 1          long named arg 2          long named arg 3          long named arg 4          since  to me  it lets you know that last     ends some  block  that ran over many lines     I personally think there is much to much made of PEP style guidelines  IDEs that enforce them  and the belief there is  only one Pythonic way to do things    If you believe the latter  go look at how to format numbers  as of now  Python supports four different ways to do it     I am sure I will be flamed by some diehards  but the compiler interpreter doesn t care if the arguments have long or short names  and - but for the indentation convention in Python - doesn t care about whitespace   The biggest problem with code is giving clarity to another human  and even yourself after months of work  to understand what is going on  where things start and end  etc

User · Answer

Adding to the vast knowledge present here   This is an answer related to the matplotlib library  import numpy as np import matplotlib as plt  matplotlib notebook linear data   np array  1  2  3  4  5  6  7  8   quadratic data   linear data  2 plt figure   xvals   range len linear data   plt barh xvals  linear data  height   0 3  color  b   plt barh xvals  quadratic data  height   0 3  left linear data  color  r     If you don t provide a semicolon at the end of the barh horizontal bar   the output is a plot   a function address  But if you use semicolons at the end of both barh lines then it only shows the plot and suppresses the output for the function address   Something like this  Comparison

User · Answer

Python uses the   as a separator  not a terminator   You can also use them at the end of a line  which makes them look like a statement terminator  but this is legal only because blank statements are legal in Python -- a line that contains a semicolon at the end is two statements  the second one blank

[python] Why is semicolon allowed in this python snippet?

Examples related to python