Python是解释的，还是编译的，或者两者都有?

根据我的理解:

解释型语言是一种高级语言，由解释器(将高级语言转换为机器代码并执行的程序)运行并执行;它每次处理一点点程序。

编译语言是一种高级语言，其代码首先由编译器(将高级语言转换为机器代码的程序)转换为机器代码，然后由执行器(另一个运行代码的程序)执行。

如果我的定义错了，请指正。

现在回到Python，我对此有点困惑。你知道Python是一种解释性语言，但它被解释为一些中间代码(如字节码或IL)，而不是机器代码。那么，哪个程序执行IM代码呢?请帮助我了解Python脚本是如何处理和运行的。

当前回答

Python(解释器)被编译。

证明:它甚至不会编译你的代码，如果它包含语法错误。

示例1:

print("This should print") 
a = 9/0

输出:

This should print
Traceback (most recent call last):
  File "p.py", line 2, in <module>
    a = 9/0
ZeroDivisionError: integer division or modulo by zero

代码编译成功。第一行执行(打印)，第二行抛出ZeroDivisionError(运行时错误)。

示例2:

print("This should not print")
/0

输出:

  File "p.py", line 2
    /0
    ^
SyntaxError: invalid syntax

结论:如果代码文件包含SyntaxError，编译失败时什么都不会执行。

2019-09-04 15:20:38

其他回答

CPU实际上只能理解机器代码。对于解释型程序，解释器的最终目标是将程序代码“解释”为机器代码。然而，现代解释语言通常不会直接解释人类代码，因为它效率太低。

Python解释器首先读取人类代码，并在将其解释为机器代码之前将其优化为一些中间代码。这就是为什么你总是需要另一个程序来运行Python脚本，不像在c++中，你可以直接运行编译后的可执行代码。例如，c:\Python27\python.exe或/usr/bin/python.

2011-07-31 13:40:52

你写的python代码被编译成python字节码，它会创建扩展名为.pyc的文件。如果是编译，问题又来了，为什么不是编译语言。

注意，这不是传统意义上的编译。通常，我们会说编译是采用高级语言并将其转换为机器代码。但它是某种汇编。编译到中间代码，而不是机器代码(希望你现在得到它)。

回到执行过程，在编译步骤中创建的pyc文件中的字节码，然后由相应的虚拟机(在我们的例子中是CPython VM)执行时间戳(称为魔数)用于验证.py文件是否被更改，这取决于创建的新pyc文件。如果pyc是当前代码，那么它简单地跳过编译步骤。

2017-11-08 10:23:49

First off, interpreted/compiled is not a property of the language but a property of the implementation. For most languages, most if not all implementations fall in one category, so one might save a few words saying the language is interpreted/compiled too, but it's still an important distinction, both because it aids understanding and because there are quite a few languages with usable implementations of both kinds (mostly in the realm of functional languages, see Haskell and ML). In addition, there are C interpreters and projects that attempt to compile a subset of Python to C or C++ code (and subsequently to machine code).

Second, compilation is not restricted to ahead-of-time compilation to native machine code. A compiler is, more generally, a program that converts a program in one programming language into a program in another programming language (arguably, you can even have a compiler with the same input and output language if significant transformations are applied). And JIT compilers compile to native machine code at runtime, which can give speed very close to or even better than ahead of time compilation (depending on the benchmark and the quality of the implementations compared).

But to stop nitpicking and answer the question you meant to ask: Practically (read: using a somewhat popular and mature implementation), Python is compiled. Not compiled to machine code ahead of time (i.e. "compiled" by the restricted and wrong, but alas common definition), "only" compiled to bytecode, but it's still compilation with at least some of the benefits. For example, the statement a = b.c() is compiled to a byte stream which, when "disassembled", looks somewhat like load 0 (b); load_str 'c'; get_attr; call_function 0; store 1 (a). This is a simplification, it's actually less readable and a bit more low-level - you can experiment with the standard library dis module and see what the real deal looks like. Interpreting this is faster than interpreting from a higher-level representation.

字节码要么被解释(请注意，在理论和实际性能上，直接解释和首先编译为一些中间表示并解释它之间存在差异)，就像参考实现(CPython)一样，要么在运行时被解释并编译为优化的机器代码，就像PyPy一样。

2011-07-31 13:43:23

根据Python官方网站，它是解释的。

https://www.python.org/doc/essays/blurb/

Python是一种解释性的、面向对象的高级编程语言……

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因为没有编译步骤…

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Python解释器和广泛的标准库是可用的…

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相反，当解释器发现错误时，它会引发例外。当程序没有捕获异常时，解释器输出堆栈跟踪。

2017-01-24 14:32:45