1、空语句 do nothing 2、保证格式完整 3、保证语义完整 4、以if语句为例: C/C++中写法: if(true) ; // do nothing else {} // do nothing python中写法: if true: pass # do nothing else: print "do something." yield #??? http://www.cnblogs.com/tqsummer/archive/2010/12/27/1917927.htm...
print(do_nothing()) # None def do_nothing(): pass print(do_nothing()) if do_nothing(): #do_nothing() 返回None布尔值为false所以不会运行到print,返回None print('...') print(do_nothing()) if not do_nothing(): #do_nothing() 返回None not do_nothing布尔值为T,所以会运行到print,返回...
一个 if ... elif ... elif ... 序列可以看作是其他语言中的 switch 或case 语句的替代。 4.2. for 语句 Python 中的 for 语句与你在 C 或 Pascal 中所用到的有所不同。 Python 中的 for 语句并不总是对算术递增的数值进行迭代(如同 Pascal),或是给予用户定义迭代步骤和暂停条件的能力(如同 C),...
(4) if 语句 代码语言:javascript 代码运行次数:0 运行 AI代码解释 i=10n=int(input("enter a number:"))ifn==i:print("equal")elif n
pass # Do nothing if rangelist[1] == 2: print "The second item (lists are 0-based) is 2" elif rangelist[1] == 3: print "The second item (lists are 0-based) is 3" else: print "Dunno" while rangelist[1] == 1: pass ...
If the element is not a member, do nothing. """ 1. 2. 3. 4. 5. 即:如果元素是成员,则从集合中删除它。如果元素不是成员,则不执行任何操作。 参数说明: discard参数必须有且仅有一个,这个参数应该是调用者集合中的子对象,否则传入则不发生任何改变。
>>> if thing is None: # 为了区分 None 和 False 的区别,这里使用 is ... print("It's nothing") ... else: ... print("It's something") ... It's nothing >>> 1. 2. 3. 4. 5. 6. 7. 8. 这看起来是一个微妙的差别,但对于Python 来说是很重要的。
Python 在语法上是编程语言中独一无二的,因为它使用空白或缩进块来屏蔽代码。像 C 这样的语言用花括号括起了一个代码块,比如一个if语句;Python 使用冒号和缩进来描述块。C 语言中的代码如下所示:if (x==4) { printf("x is equal to four\n"); printf("Nothing more to do here.\n"); } printf(...
is just a simple way to run several processes to do your work. Python environment has nothing to do with balancing load on cores/processors. multiprocessing.Processmultiprocessing.Pool If you want to control how will processor time be given to processes, you should try tweaking your OS, not ...
do it. Although that way may not be obvious at first unless you're Dutch. Nowisbetter than never. Although neverisoften better than *right* now. If the implementationishard to explain, it's a bad idea. If the implementation is easy to explain, it may be a good idea. Namespaces are...