What does "SyntaxError: Missing parentheses in call to 'print'" mean in Python?
When I try to use a
>>> 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 "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:
“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
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).
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 (
<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.