파이썬에서 '인쇄'란 무엇입니까?

파이썬에서 '인쇄'란 무엇입니까?

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나는 무엇을하는지 이해 print하지만 그 언어 요소는 어떤 "유형"인가? 함수라고 생각하는데 왜 실패할까요?

>>> print print
SyntaxError: invalid syntax

되지는 print함수? 이렇게 인쇄해야하지 않습니까?

>>> print print
<function print at ...>

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2.7 이하에서는 print성명서입니다. 파이썬 3에서는 print함수입니다. Python 2.6 또는 2.7에서 인쇄 기능을 사용하려면 다음을 수행하십시오.

>>> from __future__ import print_function
>>> print(print)
<built-in function print>

참조 이 섹션 파이썬 언어 참조 설명서에서뿐만 아니라 PEP (3105) 가 변경 이유를합니다.

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Python 3에서는 print()내장 함수 (객체)입니다.

이 전에 print이었다 문 . 데모...

파이썬 2. x :

% pydoc2.6 print

The ``print`` statement
***********************

   print_stmt ::= "print" ([expression ("," expression)* [","]]
                  | ">>" expression [("," expression)+ [","]])

``print`` evaluates each expression in turn and writes the resulting
object to standard output (see below).  If an object is not a string,
it is first converted to a string using the rules for string
conversions.  The (resulting or original) string is then written.  A
space is written before each object is (converted and) written, unless
the output system believes it is positioned at the beginning of a
line.  This is the case (1) when no characters have yet been written
to standard output, (2) when the last character written to standard
output is a whitespace character except ``' '``, or (3) when the last
write operation on standard output was not a ``print`` statement. (In
some cases it may be functional to write an empty string to standard
output for this reason.)

-----8<-----

Python 3. x :

% pydoc3.1 print

Help on built-in function print in module builtins:

print(...)
    print(value, ..., sep=' ', end='\n', file=sys.stdout)

    Prints the values to a stream, or to sys.stdout by default.
    Optional keyword arguments:
    file: a file-like object (stream); defaults to the current sys.stdout.
    sep:  string inserted between values, default a space.
    end:  string appended after the last value, default a newline.

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print is a mistake that has been rectified in Python 3. In Python 3 it is a function. In Python 1.x and 2.x it is not a function, it is a special form like if or while, but unlike those two it is not a control structure.

So, I guess the most accurate thing to call it is a statement.

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In Python all statements (except assignment) are expressed with reserved words, not addressible objects. That is why you cannot simply print print and you get a SyntaxError for trying. It's a reserved word, not an object.

Confusingly, you can have a variable named print. You can't address it in the normal way, but you can setattr(locals(), 'print', somevalue) and then print locals()['print'].

Other reserved words that might be desirable as variable names but are nonetheless verboten:

class
import
return
raise
except
try
pass
lambda

---

In Python 2, print is a statement, which is a whole different kind of thing from a variable or function. Statements are not Python objects that can be passed to type(); they're just part of the language itself, even more so than built-in functions. For example, you could do sum = 5 (even though you shouldn't), but you can't do print = 5 or if = 7 because print and if are statements.

In Python 3, the print statement was replaced with the print() function. So if you do type(print), it'll return <class 'builtin_function_or_method'>.

BONUS:

In Python 2.6+, you can put from __future__ import print_function at the top of your script (as the first line of code), and the print statement will be replaced with the print() function.

>>> # Python 2
>>> from __future__ import print_function
>>> type(print)
<type 'builtin_function_or_method'>

참고URL : https://stackoverflow.com/questions/7020417/what-is-print-in-python