I'm using Python IDLE Shell 3.10.6, and this happens:
def math(x,y):
return x*y
math(1,2)
SyntaxError: invalid syntax
math(1,2)
Traceback (most recent call last):
File "<pyshell#3>", line 1, in <module>
math(1,2)
NameError: name 'math' is not defined
Is this because Python 3.10.6 has a different syntax? I've tried the same thing in Jupyter notebook and it worked perfectly.
Can anyone help me out please? Thank you in advance!
This hasn't got anything to do with Python syntax, but quirks of the IDLE interactive shell.
In the interactive shell, you'll want to separate the definition of the function and the call into separate entries with an ENTER press, i.e. not so it reads
>>> def math(x,y):
return x*y
math(1,2)
SyntaxError: invalid syntax
(as it's attempting to parse the function to contain a trailing, unindented line)
but instead so it reads
>>> def math(x,y):
return x*y
>>> math(1, 2)
2
When I try to use a print statement in Python, it gives me this error:
>>> print "Hello, World!"
File "<stdin>", line 1
print "Hello, World!"
^
SyntaxError: Missing parentheses in call to 'print'
What does that mean?
This error message means that you are attempting to use Python 3 to follow an example or run a program that uses the Python 2 print statement:
print "Hello, World!"
The statement above does not work in Python 3. In Python 3 you need to add parentheses around the value to be printed:
print("Hello, World!")
“SyntaxError: Missing parentheses in call to 'print'” is a new error message that was added in Python 3.4.2 primarily to help users that are trying to follow a Python 2 tutorial while running Python 3.
In Python 3, printing values changed from being a distinct statement to being an ordinary function call, so it now needs parentheses:
>>> print("Hello, World!")
Hello, World!
In earlier versions of Python 3, the interpreter just reports a generic syntax error, without providing any useful hints as to what might be going wrong:
>>> print "Hello, World!"
File "<stdin>", line 1
print "Hello, World!"
^
SyntaxError: invalid syntax
As for why print became an ordinary function in Python 3, that didn't relate to the basic form of the statement, but rather to how you did more complicated things like printing multiple items to stderr with a trailing space rather than ending the line.
In Python 2:
>>> import sys
>>> print >> sys.stderr, 1, 2, 3,; print >> sys.stderr, 4, 5, 6
1 2 3 4 5 6
In Python 3:
>>> import sys
>>> print(1, 2, 3, file=sys.stderr, end=" "); print(4, 5, 6, file=sys.stderr)
1 2 3 4 5 6
Starting with the Python 3.6.3 release in September 2017, some error messages related to the Python 2.x print syntax have been updated to recommend their Python 3.x counterparts:
>>> print "Hello!"
File "<stdin>", line 1
print "Hello!"
^
SyntaxError: Missing parentheses in call to 'print'. Did you mean print("Hello!")?
Since the "Missing parentheses in call to print" case is a compile time syntax error and hence has access to the raw source code, it's able to include the full text on the rest of the line in the suggested replacement. However, it doesn't currently try to work out the appropriate quotes to place around that expression (that's not impossible, just sufficiently complicated that it hasn't been done).
The TypeError raised for the right shift operator has also been customised:
>>> print >> sys.stderr
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for >>: 'builtin_function_or_method' and '_io.TextIOWrapper'. Did you mean "print(<message>, file=<output_stream>)"?
Since this error is raised when the code runs, rather than when it is compiled, it doesn't have access to the raw source code, and hence uses meta-variables (<message> and <output_stream>) in the suggested replacement expression instead of whatever the user actually typed. Unlike the syntax error case, it's straightforward to place quotes around the Python expression in the custom right shift error message.
Unfortunately, the old xkcd comic isn't completely up to date anymore.
Since Python 3.0 you have to write:
print("Hello, World!")
And someone has still to write that antigravity library :(
There is a change in syntax from Python 2 to Python 3.
In Python 2,
print "Hello, World!"
will work but in Python 3, use parentheses as
print("Hello, World!")
This is equivalent syntax to Scala and near to Java.
Basically, since Python 3.x you need to use print with parenthesis.
Python 2.x: print "Lord of the Rings"
Python 3.x: print("Lord of the Rings")
Explanation
print was a statement in 2.x, but it's a function in 3.x. Now, there are a number of good reasons for this.
With function format of Python 3.x, more flexibility comes when printing multiple items with comma separated.
You can't use argument splatting with a statement. In 3.x if you have a list of items that you want to print with a separator, you can do this:
>>> items = ['foo', 'bar', 'baz']
>>> print(*items, sep='+')
foo+bar+baz
You can't override a statement. If you want to change the behavior of print, you can do that when it's a function but not when it's a statement.
If your code should work in both Python 2 and 3, you can achieve this by loading this at the beginning of your program:
from __future__ import print_function # If code has to work in Python 2 and 3!
Then you can print in the Python 3 way:
print("python")
If you want to print something without creating a new line - you can do this:
for number in range(0, 10):
print(number, end=', ')
In Python 3, you can only print as:
print("STRING")
But in Python 2, the parentheses are not necessary.
I could also just add that I knew everything about the syntax change between Python2.7 and Python3, and my code was correctly written as print("string") and even
print(f"string")...
But after some time of debugging I realized that my bash script was calling python like:
python file_name.py
which had the effect of calling my python script by default using python2.7 which gave the error. So I changed my bash script to:
python3 file_name.py
which of coarse uses python3 to run the script which fixed the error.
print('Hello, World!')
You're using python 3, where you need brackets when printing.
Outside of the direct answers here, one should note the other key difference between python 2 and 3. The official python wiki goes into almost all of the major differences and focuses on when you should use either of the versions. This blog post also does a fine job of explaining the current python universe and the somehow unsolved puzzle of moving to python 3.
As far as I can tell, you are beginning to learn the python language. You should consider the aforementioned articles before you continue down the python 3 route. Not only will you have to change some of your syntax, you will also need to think about which packages will be available to you (an advantage of python 2) and potential optimizations that could be made in your code (an advantage of python 3).
So I was getting this error
from trp import BoundingBox, Document
File "C:\Users\Kshitij Agarwal\AppData\Roaming\Python\Python39\site-packages\trp\__init__.py", line 31
print ip
^
SyntaxError: Missing parentheses in call to 'print'. Did you mean print(ip)?
This is a Python package error, in which Python2 has been used and you are probably running this on Python3.
One solution could be to convert Python2 print something to Python3 print(something) for every line in each file in the package folder, which is not a good idea😅. I mean, you can do it but still there are better ways.
To perform the same task, there is a package named 2to3 in Python which converts Python2 scripts to Python3 scripts. To install it, execute the 👇 command in terminal..
pip install 2to3
Then change the directory in terminal to the location where the package files are present, in my case - C:\Users\Kshitij Agarwal\AppData\Roaming\Python\Python39\site-packages\trp
Now execute the command 👇
2to3 . -w
and voila, all the Python2 files in that directory will be converted to Python3.
Note:- The above commands hold true for other operating systems as well. Only Python package path will vary as per the system.
print "text" is not the way of printing text in python as this won't work
print("text") will print said text on your screen in the command line
I have the following python code:
print 'This is a simple game.'
input('Press enter to continue . . .')
print 'Choose an option:'
...
But when I press Enter button, I get the following error:
Traceback (most recent call last):
File "E:/4.Python/temp.py", line 2, in <module>
input('Press enter to continue . . .')
File "<string>", line 0
^
SyntaxError: unexpected EOF while parsing
P.S. I am using python IDLE version 2.6 on Windows 7.
Related problem in IPython: Why does the IPython REPL tell me "SyntaxError: unexpected EOF while parsing" as I input the code?
For Python 2, you want raw_input, not input. The former will read a line. The latter will read a line and try to execute it, not advisable if you don't want your code being corrupted by the person entering data.
For example, they could do something like call arbitrary functions, as per the following example:
def sety99():
global y
y = 99
y = 0
input ("Enter something: ")
print y
If you run that code under Python 2 and enter sety99(), the output will 99, despite the fact that at no point does your code (in its normal execution flow) purposefully set y to anything other than zero (it does in the function but that function is never explicitly called by your code). The reason for this is that the input(prompt) call is equivalent to eval(raw_input(prompt)).
See here for the gory details.
Keep in mind that Python 3 fixes this. The input function there behaves as you would expect.
In Python 2, input() strings are evaluated, and if they are empty, an exception is raised. You probably want raw_input() (or move on to Python 3).
In Python 2.x, input() is equivalent to eval(raw_input()). And eval gives a syntax error when you pass it an empty string.
You want to use raw_input() instead.
If you use input on Python 2.x, it is interpreted as a Python expression, which is not what you want. And since in your case, the string is empty, an error is raised.
What you need is raw_input. Use that and it will return a string.
I wrote a code and it is getting compiled on my PC with Python3. But Showing error while uploading to Codechef server. Please suggest, I am coding for the first time in Python 3.
Traceback (most recent call last):
File "/run-ls7W2DcLmzUs9GNKbLGN/solution.py", line 41, in <module>
l,r,k=map(int,input().split())
File "<string>", line 1
9 23 1
^
SyntaxError: invalid syntax
You're using python2.x which evaluates the string you enter for input. Change the function from input to raw_input and you should be all set.
If you want the code to work for both python2.x and python3.x, you could do a simple little hack like this at the top of your script:
try:
#This raises `NameError` on python3.x since `raw_input` is renamed to `input`
input = raw_input
except NameError:
pass
It's not pretty, but it works (and I've used things like this on occasion). Ultimately, this shadows the builtin input on python2.x, but that's really not a big deal. You probably don't want to be using that builtin for any serious coding anyway.
According to this: http://code.activestate.com/lists/python-list/413540/, tokenize.generate_tokens should be used and not tokenize.tokenize.
This works perfectly fine in Python 2.6. But it does not work anymore in Python 3:
>>> a = list(tokenize.generate_tokens(io.BytesIO("1\n".encode()).readline))
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python3.2/tokenize.py", line 439, in _tokenize
if line[pos] in '#\r\n': # skip comments or blank lines
However, also in Python 3, this works (and returns also the desired output):
a = list(tokenize.tokenize(io.BytesIO("1\n".encode()).readline))
According to the documentation, it seems like tokenize.tokenize is the new way to use this module: http://docs.python.org/py3k/library/tokenize.html. tokenize.generate_tokens isn't even documented anymore.
But, why is there still a generate_tokens function in this module, if it's not documented? I haven't found any PEP regarding this.
I'm trying to maintain a code base for Python 2.5-3.2, should I call generate_tokens for Python 2 and tokenize for Python 3? Aren't there any better ways?
generate_tokens seems to be really a strange thing in Python 3. It doesn't work like in Python 2. However, tokenize.tokenize behaves like the old Python 2 tokenize.generate_tokens. Therefore I wrote a little workaround:
import tokenize
if sys.hexversion >= 0x03000000d:
tokenize_func = tokenize.tokenize
else:
tokenize_func = tokenize.generate_tokens
Now I just use tokenize_func, which works without problems.
generate_tokens in python3 is undocumented but not uncommented. it's there for backward compatibility, so you can use it, but it's probably better to use the changed tokenize instead...