Warning: file_get_contents(/data/phpspider/zhask/data//catemap/2/python/351.json): failed to open stream: No such file or directory in /data/phpspider/zhask/libs/function.php on line 167

Warning: Invalid argument supplied for foreach() in /data/phpspider/zhask/libs/tag.function.php on line 1116

Notice: Undefined index: in /data/phpspider/zhask/libs/function.php on line 180

Warning: array_chunk() expects parameter 1 to be array, null given in /data/phpspider/zhask/libs/function.php on line 181
Python中循环的执行_Python_For Loop_If Statement - Fatal编程技术网

Python中循环的执行

Python中循环的执行,python,for-loop,if-statement,Python,For Loop,If Statement,当我运行该函数时,它只在屏幕上输出一条语句。 那么为什么for循环只执行一次呢 return终止函数,将return False移动到循环后: def search_for_element(L, char): for i in L: if i == char: return True else: return False 或者简单地说: def search_for_element(L, char):

当我运行该函数时,它只在屏幕上输出一条语句。
那么为什么for循环只执行一次呢

return
终止函数,将
return False
移动到循环后:

def search_for_element(L, char):
    for i in L:
        if i == char:
            return True
        else:
            return False
或者简单地说:

def search_for_element(L, char):
    for i in L:
        if i == char:
            return True
    return False
尽管需要注意,后者并不完全等同,因为它也测试身份(不仅仅是相等)。这只会在非常不寻常的情况下起作用,例如,
numpy.NAN==numpy.NAN
False
,但[numpy.NAN]中的
numpy.NAN是
True

因此,单班轮替代方案是:

def search_for_element(L, char):
    return char in L
def search_for_element(L, char):
    return any(char == i for i in L)