第一天学python，做一个作业
题目：字符串按单词反转（必须保留所有空格）。‘I love china!’ 转化为 ‘china! love I’
import string
s = 'I love china!'
s1=list(s.split())
#构建一个空数组
x=[]
#反向遍历数组
for c in reversed(s1):
x.append(c)
#按空格连接字符串
print(' '.join(x))
def reverse(str_list, start, end):
while start < end:
str_list[start], str_list[end] = str_list[end], str_list[start]
print('r_str_list_start:',str_list[start])
print('r_str_list_end:',str_list[end])
start += 1
end -= 1
setence = ' Hello, how are you? Fine. '
str_list = list(setence)
print('str_list:', str_list)
i = 0
while i < len(str_list):
if str_list[i] != ' ':
start = i
end = start + 1
print('start:', start)
print('end:',end)
while(end < len(str_list)) and str_list[end] != ' ':
end += 1
print('s_end:', end)
reverse(str_list, start, end - 1)
i = end
print('i:',i)
else:
i += 1
print(str_list)
str_list.reverse()
print(''.join(str_list))
看看打印输出结果
str_list: [' ', 'H', 'e', 'l', 'l', 'o', ',', ' ', 'h', 'o', 'w', ' ', 'a', 'r', 'e', ' ', 'y', 'o', 'u', '?', ' ', ' ', ' ', 'F', 'i', 'n', 'e', '.', ' ', ' ', ' ', ' '] #输出列表
start: 1 #i=1时，执行
start=1, end +=1
end: 2
s_end: 3
s_end: 4
s_end: 5
s_end: 6
s_end: 7 #index为7时，遇到第一个' '
r_str_list_start: ,
r_str_list_end: H
r_str_list_start: o
r_str_list_end: e
r_str_list_start: l
r_str_list_end: l
i: 7
start: 8
end: 9
s_end: 10
s_end: 11
r_str_list_start: w
r_str_list_end: h
i: 11
start: 12
end: 13
s_end: 14
s_end: 15
r_str_list_start: e
r_str_list_end: a
i: 15
start: 16
end: 17
s_end: 18
s_end: 19
s_end: 20
r_str_list_start: ?
r_str_list_end: y
r_str_list_start: u
r_str_list_end: o
i: 20
start: 23
end: 24
s_end: 25
s_end: 26
s_end: 27
s_end: 28
r_str_list_start: .
r_str_list_end: F
r_str_list_start: e
r_str_list_end: i
i: 28
[' ', ',', 'o', 'l', 'l', 'e', 'H', ' ', 'w', 'o', 'h', ' ', 'e', 'r', 'a', ' ', '?', 'u', 'o', 'y', ' ', ' ', ' ', '.', 'e', 'n', 'i', 'F', ' ', ' ', ' ', ' ']
Fine. you? are how Hello,
好像成功了，感觉是要好些，的确是理解偏差
