Syntax error in Python IDLE (Mac OS X) because of indentation

Question

I'm assuming this is going to be stupidly easy to answer, yet I've searched all over and can't find an answer. I'm learning Python and trying to run some very simple code, but I keep getting a syntax error any time I try to do something after an indented block. For example:

x = [1,2,3];
for i in x:
    print(i);
print('finished');

When I run this code, I get a syntax error on the print('finished') part. Any time I try to run anything by unindenting after a block like a loop or if statement, I get this error. I'm running Python 3.2.3 in IDLE on Mac OS X Lion.

UPDATE: seems this wasn't as easy as I thought and maybe I'm trying to get something to work that is pointless. I guess the shell only runs multiline statements when you're running a block that indents, but the moment you get back to the top level it executes the statements. Since I'll usually be working with files, most likely in Django, won't matter in the end. Thanks for all the amazingly fast responses though.

Not your problem, but Python doesn't need semicolons to end lines. — Daniel Roseman
– Daniel Roseman, Commented May 31, 2012 at 21:28

sarnold · Accepted Answer · 2012-05-31 21:14:02Z

3

At least the python interactive interpreter on my Ubuntu system requires a newline to end the block:

>>> x = [1,2,3];
>>> for i in x:
...     print(i);
... print('finished');
  File "<stdin>", line 3
    print('finished');
        ^
SyntaxError: invalid syntax
>>> x = [1,2,3];
>>> for i in x:
...     print(i);
... 
1
2
3
>>> print('finished');
finished

Funny enough, the python interpreter does not require the blank line when run on scripts:

$ cat broken.py 
#!/usr/bin/python

x = [1,2,3];
for i in x:
    print(i);
print('finished');

$ ./broken.py 
1
2
3
finished
$

answered May 31, 2012 at 21:14

sarnold

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5 Comments

abarnert Over a year ago

The language itself doesn't require a newline, but the basic interactive interpreter can't figure out that an indented block has ended without one, and same for IDLE. (Some other IDEs may be a bit smarter.)

Rocket04 Over a year ago

Thing is, how do I add that newline character it wants? If I hit enter inside the loop it goes to another line, but if I unindent and hit enter, it executes the code

sarnold Over a year ago

@Rocket04: If you are defining a function or method, it'll by necessity wait until the entire function is defined and called before it can execute the code.

Rocket04 Over a year ago

@sarnold There's no function at all, the code I'm running is only what I typed in this example. I'm starting to think I'm looking at this the wrong way. The shell may just not be made to run this code, it wants you to run blocks separately. If I want to run multiple blocks, I guess I can run them one after the other or simply use a file/module

sarnold Over a year ago

Yeah, if you're just fiddling with the thing as a handy REPL source, then it doesn't much matter when it gets around to executing the loop vs executing the statements following the loop. It really only matters when you're defining a function or method for later execution.

Tremmors · Accepted Answer · 2012-05-31 21:12:27Z

1

Take out all your semicolons.

x = [1,2,3]
for i in x:
    print(i)
print('finished')

answered May 31, 2012 at 21:12

Tremmors

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2 Comments

abarnert Over a year ago

This is definitely a good suggestion for other reasons, but completely irrelevant to the problem at hand.

Tremmors Over a year ago

The script in my post works on my mac running python 3.2.3 and my windows machine running 3.2.

user278064 · Accepted Answer · 2012-05-31 21:14:27Z

1

Insert a newline after print(i) (also on windows)

x = [1, 2, 3]
for i in x:
    print(i)

print('finished')

answered May 31, 2012 at 21:14

user278064

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Comments

Ned Deily · Accepted Answer · 2012-06-04 23:08:32Z

1

Are you trying to enter this code in IDLE's default Python Shell window? You are better off opening an IDLE editor window (menu item File -> New Window) and running the code from there (menu item Run -> Run Module). Indenting in the shell window can get confusing and it is difficult to correct mistakes.

edited Jun 4, 2012 at 23:08

answered May 31, 2012 at 22:04

Ned Deily

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