文章首发公众号：CoderMrWu ，每周分享优质技术文章和教训，欢送大家关注，独特交换。
明天看了篇文章总结了 40 种Python String 类型的罕用语法，觉着很乏味，翻译重新整理分享给大家。只管有些语法你可能用不到，但也算是把握一种奇思巧技。
1/ 创立字符串
s1 = 'This is a test.'2/ 应用 print 语句查看输入
# python3/python2>>> print('this is a test.')this is a test.# python3/python2>>> print ('test')test# python2>>> print '123'1233/ 单行查看输入
>>> s1 = 'this is'>>> s2 = ' a test'>>> print(s1+s2)this is a test4/ 单行 n 查看输入
>>> print(s1+'\n'+s2)this is a test5/ 字符串下标表示法
>>> print(s1[0])t>>> print(s1[1])h>>> print(s1[8])Traceback (most recent call last): File "<input>", line 1, in <module>IndexError: string index out of range6/ 下标字符串相加
>>> print(s1[1]+s1[3]+s1[4])hs7/ 切片字符串
>>> print(s1[0:5])this>>> print(s1[0:])this is>>> print(s1[:])this is>>> print(s1[:-1])this i>>> print(s1[::2])ti s8/ 负索引切片
>>> print(s1[-5:-1])is i>>> print(s1[-1::-1]) # 反转字符串si siht9/ %格式化操作符
>>> print('this is a %s' % 'test')this is a test>>> print('this is a %(test)s' % {'test':'12345'})this is a 1234510/ 带整数的%
>>> print('1+1 = %(num)01d' % {'num': 2})1+1 = 2>>> print('1+1 = %(num)02d' % {'num': 2})1+1 = 02>>> print('1+1 = %(num)03d' % {'num': 2})1+1 = 00211/ %用于站位
>>> print( '%(a)s %(n)03d - program is the best.' % {'a':'Python','n':3})Python 003 - program is the best.12/ 利用 \n 分拆字符串
>>> print(' %(a)s %(n)03d - program is the best \n %(a)s helped me understand programming.' % {"a":"Python","n":3})Python 003 - program is the bestPython helped me understand programming.13/ 多个\n
>>> print(' I love %(a)s. \n I like %(b)s. \n I like to %(c)s. \n my %(d)s is %(num)03d.'%{"a":"to code","b":"ice-cream","c":"travel","d":"age","num":32})I love to code.I like ice-cream.I like to travel.my age is 032.14/ 其余形式应用%
>>> print('Hello everyone I am using Python %d.7 version.' % 3.7)Hello everyone I am using Python 3.7 version.>>> print('%s %s %d %d %f %f' % ('Hercules', 'Zeus', 100, 20, 3.2, 1))Hercules Zeus 100 20 3.200000 1.000000>>> print('This is a +%d integer' % 10)This is a +10 integer>>> print('This is a negative -%d integer' % 250)This is a negative -250 integer>>> print('This is a confused -%d integer' % 300)This is a confused -300 integer15/ 字串符转为整数
>>> s3 = '123'>>> print(10*int(s3)) # 乘法1230>>> print(10*s3) # 倍数123123123123123123123123123123>>> print('1'+'45')145>>> print('1'+45)Traceback (most recent call last): File "<stdin>", line 1, in <module>TypeError: can only concatenate str (not "int") to str>>> print(float('1')+float('45'))46.016/ 获取单个字符在字符串中呈现的次数
>>> text = 'this is a test.'>>> print(text.count('t'))3>>> print(text.count('is'))217/ 将字符串变为大写
>>> text = 'this is a test.'>>> print(text.upper())THIS IS A TEST.18/ 将字符串变为小写
>>> text = 'THIS IS A TEST.'>>> print(text.upper())this is a test.19/ 组合字符串
>>> ' '.join(text)'t h i s i s a t e s t .'>>> ','.join(['hello', 'Dean'])'hello,Dean'20/ 分拆字符串
>>> text = 'this is a test.'>>> print(text.split(' '))['this', 'is', 'a', 'test.']21/ 判断字符串是否是大写
>>> text'this is a test.'>>> up_text = text.upper()>>> print(up_text.isupper())True22/ 判断字符串是否是小写
>>> low_text = text.lower()>>> print(low_text.islower())True23/ 判断字符串是否有字母数字形成
>>> text1 = 'Lession 01'>>> print(text1.isalnum())False>>> text2 = 'Lession01'>>> print(text2.isalnum())True24/ 获取字符串的长度
>>> text'this is a test.'>>> print(len(text))1525/ 将字符串转化为 10 进制的 asscii 码
>>> print(ord('A'))65>>> print(ord('B'))66>>> print(ord('a'))97>>> print(ord('b'))9826/ 将 10 进制的 asscii 码转化为字符串
>>> print(chr(65))A>>> print(chr(42))*>>> print(chr(118))v>>> print(chr(60))<27/ 转义字符
>>> print('What\'s up?')What's up?>>> # the apostrophe is not needed in this case.>>> print("What's up?")What's up?>>> # the apostrophe is needed to add on the quotes to the text>>> print("\"What's up?\"")"What's up?">>> # triple quotes can escape single, double, and a lot more.>>> print("""What's up? Does the "" need an escape?""")What's up? Does the "" need an escape?28/ 应用逗号格式化字符串
>>> print('这里有', 10, '个苹果')这里有 10 个苹果29/ format 格式化字符串
>>> text'this is a test.'>>> print('This is a {}'.format(text))This is a this is a test.>>> print('Number {1} and number {0}'.format(100, 200)) # keyword positionNumber 200 and number 10030/ format 中通过名字传递字符
>>> print('这里有{num}个{type}。'.format(num=10, type='苹果'))这里有10个苹果。>>> tmp = {'num': 10, 'type': '苹果'}>>> print('这里有{num}个{type}。'.format(**tmp))这里有10个苹果。31/ format 中通过参数程序传递字符
>>> print('这里有{1}个{0}。'.format('苹果',10))这里有10个苹果。32/ format 中拜访对象属性
>>> class Rectangle: def __init__(self, length, width): self.length = length self.width = width def __str__(self): return 'Rectangle({self.length}, {self.width})'.format(self=self)>>> rect = Rectangle(10, 5.5)>>> print(rect.__str__())Rectangle(10, 5.5)33/ 对齐文本
>>> print('{:<10}'.format('X')) # left alignX>>> print('{:>10}'.format('X')) # right align X>>> print('{:^10}'.format('X')) # center X>>> print('{:?^10}'.format('X')) # add a fill character????X?????34/ 格式化二进制、八进制和十六进制
>>> print('Binary number: {0:b}'.format(50))Binary number: 110010>>> print('Octal number: {0:o}'.format(100))Octal number: 144>>> print('Hexadecimal number: {0:x}'.format(2555))Hexadecimal number: 9fb35/ 应用逗号作为分隔符
>>> print('{:,}'.format(2783727282727))2,783,727,282,727>>> print('{:.2%}'.format(90.60/100))90.60%36/ 应用f来格式化字符串
>>> item_1, item_2, item_3 = 'computer', 'mouse', 'browser'>>> print(f"He uses a {item_1}.")He uses a computer.>>> print(f"He uses a {item_2} and a {item_3}.")He uses a mouse and a browser.>>> print(f"He uses a {item_1} 3 times a day.")He uses a computer 3 times a day.37/ 应用模板格式化字符串
# docs: https://docs.python.org/3/library/string.html#template-strings>>> from string import Template>>> poem = Template('$x are red and $y are blue')>>> print(poem.substitute(x='roses', y='violets'))roses are red and violets are blue38/ 字符串的遍历
>>> text'this is a test.'>>> for item in text:... print(item)...thisisatest.39/ 应用 while 循环
>>> i = 0>>> while i < len(text): print(text[i])40/ 应用三引号保留字符串
>>> def triple_quote_docs(): """ In the golden lightning Of the sunken sun, O'er which clouds are bright'ning, Thou dost float and run, Like an unbodied joy whose race is just begun. """ return>>> print(triple_quote_docs.__doc__) In the golden lightning Of the sunken sun, O'er which clouds are bright'ning, Thou dost float and run, Like an unbodied joy whose race is just begun.>>>参考：
- https://pysnakeblog.blogspot.com/2019/09/top-40-python-string-processing-in.html