girls = ['gujin','yangmi','zhengshuang']
my_girls = []
a = len(girls)
a = int(a)
while a >= 0:
a=a-1
girl = girls.pop()
my_girls.append(girl)
continue
for my_girl in my_girls:
print(my_girl)
报错:
Traceback (most recent call last):
File "girls4.py", line 6, in
girl = girls.pop()
IndexError: pop from empty list
这段执行不报错:
girls = ['gujin','yangmi','zhengshuang']
my_girls = []
while girls:
girl = girls.pop()
my_girls.append(girl)
for my_girl in my_girls:
print(my_girl)
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执行循环语句时,当a=1,判断a>=0满足,执行a=a-1,此时a=0,继续判断,a>=0仍然满足,执行a=a-1,此时a=-1,执行girl=girls.pop()必然出错,因为索引下标从0开始,所以直接把whilea>=0改成whilea>0,这样当a=0时会直接跳出循环,就不会报错了。
while判断不要等号。whilea>0:
girls=['gujin','yangmi','zhengshuang']
my_girls=[]
a=len(girls)
a=int(a)
whilea>=0:
a=a-1
ifa>=0:
girl=girls.pop()
my_girls.append(girl)
else:
break
formy_girlinmy_girls:
print(my_girl)
我自己是这么理解的,a是我定义的变量按照我原来的写法,a分别为3,2,1,0,while要执行4次
但是我的girls列表,只满足执行3次就是空列表,取无可取