return 语句的目的是什么?它与印刷有何不同?

问题描述

什么是return语句的简单基本解释，在Python中如何使用?

What is the simple basic explanation of what the return statement is, how to use it in Python?

它和print语句有什么区别?

推荐答案

print() 函数在控制台中写入，即打印"一个字符串.return 语句使你的函数退出并将一个值返回给它的调用者.一般来说，函数的重点是接受输入并返回一些东西.return 语句在函数准备好向其调用者返回值时使用.

The print() function writes, i.e., "prints", a string in the console. The return statement causes your function to exit and hand back a value to its caller. The point of functions in general is to take in inputs and return something. The return statement is used when a function is ready to return a value to its caller.

例如，这是一个同时使用 print() 和 return 的函数:

For example, here's a function utilizing both print() and return:

def foo():
    print("hello from inside of foo")
    return 1

现在您可以运行调用 foo 的代码，如下所示:

Now you can run code that calls foo, like so:

if __name__ == '__main__':
    print("going to call foo")
    x = foo()
    print("called foo")
    print("foo returned " + str(x))

如果您将其作为脚本(例如 .py 文件)而不是在 Python 解释器中运行，您将获得以下输出:

If you run this as a script (e.g. a .py file) as opposed to in the Python interpreter, you will get the following output:

going to call foo
hello from inside foo
called foo   
foo returned 1

我希望这会让它更清楚.解释器将返回值写入控制台，这样我就能明白为什么有人会感到困惑.

I hope this makes it clearer. The interpreter writes return values to the console so I can see why somebody could be confused.

下面是来自解释器的另一个例子，它证明了这一点:

Here's another example from the interpreter that demonstrates that:

>>> def foo():
...     print("hello from within foo")
...     return 1
...
>>> foo()
hello from within foo
1
>>> def bar():
...   return 10 * foo()
...
>>> bar()
hello from within foo
10

可以看到，当 bar() 调用 foo() 时，1 并没有写入控制台.相反，它用于计算从 bar() 返回的值.

You can see that when foo() is called from bar(), 1 isn't written to the console. Instead it is used to calculate the value returned from bar().

print() 是一个会导致副作用的函数(它在控制台中写入一个字符串)，但会从下一条语句继续执行.return 使函数停止执行并将值返回给调用它的任何对象.

print() is a function that causes a side effect (it writes a string in the console), but execution resumes with the next statement. return causes the function to stop executing and hand a value back to whatever called it.

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