一个学生问，另一个有同样问题的学生回答:)

fruits=['orange', 'grape', 'kiwi', 'apple', 'mango', 'fig', 'lemon']
newList = []
for fruit in fruits:
    newList.append(fruit.upper())
print(newList)

你可以尝试使用:

my_list = ['india', 'america', 'china', 'korea']

def capitalize_list(item):
    return item.upper()

print(list(map(capitalize_list, my_list)))

这可以通过列表推导来完成

>>> [x.lower() for x in ["A", "B", "C"]]
['a', 'b', 'c']
>>> [x.upper() for x in ["a", "b", "c"]]
['A', 'B', 'C']

或者使用映射函数

>>> list(map(lambda x: x.lower(), ["A", "B", "C"]))
['a', 'b', 'c']
>>> list(map(lambda x: x.upper(), ["a", "b", "c"]))
['A', 'B', 'C']

一个学生问，另一个有同样问题的学生回答:)

fruits=['orange', 'grape', 'kiwi', 'apple', 'mango', 'fig', 'lemon']
newList = []
for fruit in fruits:
    newList.append(fruit.upper())
print(newList)

列表理解是我的做法，这是“python”的方式。下面的文字记录展示了如何将一个列表全部转换为大写，然后再转换回小写:

pax@paxbox7:~$ python3
Python 3.5.2 (default, Nov 17 2016, 17:05:23) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.

>>> x = ["one", "two", "three"] ; x
['one', 'two', 'three']

>>> x = [element.upper() for element in x] ; x
['ONE', 'TWO', 'THREE']

>>> x = [element.lower() for element in x] ; x
['one', 'two', 'three']

除了更容易阅读(对许多人来说)，列表推导式也在速度竞赛中获胜:

$ python2.6 -m timeit '[x.lower() for x in ["A","B","C"]]'
1000000 loops, best of 3: 1.03 usec per loop
$ python2.6 -m timeit '[x.upper() for x in ["a","b","c"]]'
1000000 loops, best of 3: 1.04 usec per loop

$ python2.6 -m timeit 'map(str.lower,["A","B","C"])'
1000000 loops, best of 3: 1.44 usec per loop
$ python2.6 -m timeit 'map(str.upper,["a","b","c"])'
1000000 loops, best of 3: 1.44 usec per loop

$ python2.6 -m timeit 'map(lambda x:x.lower(),["A","B","C"])'
1000000 loops, best of 3: 1.87 usec per loop
$ python2.6 -m timeit 'map(lambda x:x.upper(),["a","b","c"])'
1000000 loops, best of 3: 1.87 usec per loop