Pass指忽略…就是这么简单。如果给定的条件为真，并且下一个语句是通过的，它将忽略该值或迭代并继续执行下一行。

例子:

for i in range (1, 100):
    if i%2 == 0:
        pass
    else:
        print(i)

输出:输出1-100之间的所有奇数

这是因为一个偶数的模量等于零，因此它会忽略这个数字，继续下一个数字。由于奇数的模量不等于零，循环的else部分被执行并打印出来。

在Python中，pass基本上什么都不做，但与注释不同的是，它不会被解释器忽略。所以你可以在很多地方利用它，把它变成占位符:

1:可以在课堂上使用

class TestClass:
    pass

2:可以在循环语句和条件语句中使用:

if (something == true):  # used in conditional statement
    pass

while (some condition is true):  # user is not sure about the body of the loop
    pass

3:可用于功能:

def testFunction(args): # The programmer wants to implement the body of the function later
    pass

当程序员暂时不想给出实现，但仍然想创建某个类/函数/条件语句以供以后使用时，通常使用Pass。由于Python解释器不允许出现空白或未实现的类、函数或条件语句，因此会给出一个错误:

IndentationError:期望一个缩进的块

Pass可以在这种情况下使用。

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。

如果你想导入一个模块，如果它存在，并且忽略导入它，如果该模块不存在，你可以使用下面的代码:

try:
    import a_module
except ImportError:
    pass
# The rest of your code

如果您避免编写pass语句并继续编写其余代码，则会引发IndentationError，因为打开except块后的行没有缩进。

你可以说pass意味着一个NOP(无操作)操作。看完这个例子，你就会清楚了:

C程序

#include<stdio.h>

void main()
{
    int age = 12;
  
    if( age < 18 )
    {
         printf("You are not adult, so you can't do that task ");
    }
    else if( age >= 18 && age < 60)
    {
        // I will add more code later inside it 
    }
    else
    {
         printf("You are too old to do anything , sorry ");
    }
}

现在你要怎么用Python写这个:

age = 12

if age < 18:

    print "You are not adult, so you can't do that task"

elif age >= 18 and age < 60:

else:

    print "You are too old to do anything , sorry "

但是您的代码会给出一个错误，因为在elif之后需要一个缩进的块。下面是pass关键字的作用。

age = 12

if age < 18:

    print "You are not adult, so you can't do that task"

elif age >= 18 and age < 60:
    
    pass

else:

    print "You are too old to do anything , sorry "

现在我想你们都清楚了。

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!