我在学习Python的过程中,我已经到了关于pass语句的部分。我正在使用的指南将其定义为通常用作占位符的空语句。

但我还是不太明白这是什么意思。pass语句将被使用的简单/基本情况是什么?为什么需要它?


当前回答

Pass is usually helpful when you are writing code to design a game or something of that type , now as you proceed with the code , you would realize that , there are some functions you don't want to move ahead and want to leave it untouched and move further on with the code and then revisit the function later , but as you do so , the compiler would obviously thrown an error saying it isn't either recognized and all sorts of other things!! In this condition you use pass so that the compiler would simply neglect the function and move further on with the code !!

例如:

if __name__ = "__main__":
pass
print("Hello World!")

在这里,编译器将忽略if name部分,并按照指示打印Hello World !!

谢谢!

其他回答

首先,如果你想写一个block,像这样:

if statement:
    pass
for i in range(abc):
    pass
def func():
    pass

pass can是一个占位符。

其次,它可以让你与IDE“交流”: 当你想让你的IDE像这样递减缩进: 如果你的程序写在这里:

class abc(parent):
    def __init__(self, params):
        self.params=params
        if d:
            return
        else:
            return
        # cursor in there

现在你的缩进计数是2,但你希望它在下一行是1。 你可以输入一个pass,你的程序是这样的:

class abc(parent):
    def __init__(self, params):
        self.params=params
        if d:
            return
        else:
            return
        pass# cursor in there

并返回。它会让你快乐:

class abc(parent):
    def __init__(self, params):
        self.params=params
        if d:
            return
        else:
            return
        pass
    # cursor in there

现在缩进计数是1。

正如书中所说,我只把它用作临时占位符,也就是说,

# code that does something to to a variable, var
if var == 2000:
    pass
else:
    var += 1

然后填充var == 2000的场景。

Pass只是空的表示代码。

例如,pass用于创建一个空类或函数,如下所示:

class Test:
    pass

def test():
    pass

但是,如果一个类或函数真的没有任何东西,甚至通过如下所示:

class Test:
    # pass

def test():
    # psss

出现如下错误:

SyntaxError:解析时意外的EOF

正如我之前所说,pass只是空的指示代码,所以如果在pass之后有一些代码,代码的工作方式如下所示:

class Test:
    pass
    x = "Hello World"

def test():
    pass
    return "Hello World"

print(Test.x) # Hello World
print(test()) # Hello World

pass语句什么也不做。当语法上需要语句,但程序不需要操作时,可以使用它。

Pass is usually helpful when you are writing code to design a game or something of that type , now as you proceed with the code , you would realize that , there are some functions you don't want to move ahead and want to leave it untouched and move further on with the code and then revisit the function later , but as you do so , the compiler would obviously thrown an error saying it isn't either recognized and all sorts of other things!! In this condition you use pass so that the compiler would simply neglect the function and move further on with the code !!

例如:

if __name__ = "__main__":
pass
print("Hello World!")

在这里,编译器将忽略if name部分,并按照指示打印Hello World !!

谢谢!