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day10-字符串作业2

article 2025/1/12 2:56:00

编写一个程序，交换指定字典的key和value。

  例如:dict1={'a':1, 'b':2, 'c':3}  -->  dict1={1:'a', 2:'b', 3:'c'}

dict1={'a': 1, 'b': 2, 'c': 3}
dict2 = {}
for key in dict1:
    new_key = dict1[key]
    new_vaule = key
    dict2[new_key] = new_vaule
print(dict2)        # {1: 'a', 2: 'b', 3: 'c'}

编写一个程序，提取指定字符串中所有的字母，然后拼接在一起产生一个新的字符串

   例如: 传入'12a&bc12d-+'   -->  'abcd'

str1 = '12a&bc12d-+'
str2 = ''
for x in str1:
    if 'a' <= x <= 'z' or 'A' <= x <= 'Z':
        str2 += x
print(str2)     # abcd

写一个自己的capitalize函数，能够将指定字符串的首字母变成大写字母

  例如: 'abc' -> 'Abc'   '12asd'  --> '12asd'

str1 = '12asd'
str2 = ''
for x in str1:
    if 'a' <= x <= 'z':
        m = chr(ord(x) - 32)
        str2 = str1.replace(x, m)
        break
print(str2)

写程序实现endswith的功能，判断一个字符串是否已指定的字符串结束

   例如: 字符串1:'abc231ab' 字符串2:'ab' 函数结果为: True
        字符串1:'abc231ab' 字符串2:'ab1' 函数结果为: False

str1 = 'abc231ab'
str2 = '1ab'
l2 = len(str2)
if str2 in str1:
    if str1[-l2:] == str2:
        print('True')
else:
    print('False')

写程序实现isdigit的功能，判断一个字符串是否是纯数字字符串

   例如: '1234921'  结果: True
         '23函数'   结果: False
         'a2390'    结果: False

str1 = input('输入：')
for x in str1:
    if not ('0' <= x <= '9'):
        print('False')
        break
else:
    print('True')

写程序实现upper的功能，将一个字符串中所有的小写字母变成大写字母

    例如: 'abH23好rp1'   结果: 'ABH23好RP1'

str1 = 'abH23好rp1'
str2 = ''
for x in str1:
    if 'a' <= x <= 'z':
        str2 += chr(ord(x) - 32)
    else:
        str2 += x
print(str2)     # ABH23好RP1

写程序获取指定序列中元素的最大值。如果序列是字典，取字典值的最大值

   例如: 序列:[-7, -12, -1, -9]    结果: -1   
        序列:'abcdpzasdz'    结果: 'z'  
        序列:{'小明':90, '张三': 76, '路飞':30, '小花': 98}   结果: 98

# xl1 = [-7, -12, -1, -9]
# xl1 = 'abcdpzasdz'
xl1 = {'小明': 90, '张三': 76, '路飞': 30, '小花': 98}
list1 = []
if type(xl1) == dict:
    for x in xl1:
        list1.append(xl1[x])
    list1.sort()
    print('最大值：', list1[-1])
else:
    max1 = xl1[0]
    for x in xl1:
        if x > max1:
            max1 = x
    print('最大值：', max1)

写程序实现replace函数的功能，将指定字符串中指定的旧字符串转换成指定的新字符串

    例如: 原字符串: 'how are you? and you?'   旧字符串: 'you'  新字符串:'me'  结果: 'how are me? and me?'

msg = 'how are you? and you?'
old_str = 'you'
new_str = 'me'
new_msg = ''
index = 0
while True:
    if msg[index:index+3] == old_str:
        new_msg += new_str
        index += 3
    else:
        new_msg += msg[index]
        index += 1
    if index == len(msg):
        break
print(new_msg)

写程序实现split的功能，将字符串中指定子串作为切割点对字符串进行切割

例如：原字符串: 'how are you? and you?'   切割点: 'you'  结果: ['how are ', '? and ', '?']

msg = 'how are you? and you?'
str1 = 'you'
str2 = ''
list1 = []
index = 0
you_index = 0
count1 = msg.count(str1)
count2 = 0
while True:
    if msg[index:index+3] == str1:
        list1.append(msg[you_index:index])
        you_index = index + 3
        index += 3
        count2 += 1
    else:
        index += 1
    if count1 == count2:
        list1.append(msg[index:])
        break
print(list1)