Python学习笔记 - 字符串

#---------------------------------------------------------------------------------------
# 字符串连接 : 方法1 ‘+‘
str0 = ‘hello‘
str1 = "python"
print(str0 + str1) #‘hellopython‘

# 字符串连接 : 方法2 连接对象.join() : 在每个单词之间用连接对象连接起来
lst = [‘www‘,‘google‘,‘com‘]
lst_join = ".".join(lst)
print(lst_join)    #‘www.google.com‘


#---------------------------------------------------------------------------------------
# 格式化字符串1: 占位符‘{}‘
name = ‘Tom‘
age = 20
addr = "上海市"
info = ‘{0},{1},{2}‘.format(name, age, addr)
print(info)    #‘Tom,20,上海市‘


#---------------------------------------------------------------------------------------
# 格式化字符串2: 占位符‘{}‘
print("{name},{age},{addr}".format(name = "Tom", age = 22, addr = "上海市")) #‘Tom, 22, 上海市‘

#---------------------------------------------------------------------------------------
# 格式化字符串3: %
num = 100
str_tmp = "%d years" % num
print(str_tmp)    #‘100 years‘

lang = "python"
print("I love %(program)s" % {"program" : lang})    #"I love python"


#---------------------------------------------------------------------------------------
# len() : 获取字符串长度
str1 = "hello"
print(len(str1))    #5

#---------------------------------------------------------------------------------------
# 字符串.isalpha() : 判断字符串对象是否全部为字母, True(全部为字符), False(含非字母)
str2 = "world2"
str3 = ‘hehe he‘
print(‘str1 : ‘ + str(str1.isalpha()))    #True
print(‘str2 : ‘ + str(str2.isalpha()))    #False
print(‘str3 : ‘ + str(str3.isalpha()))    #False


#--------------------------------------------------
# str.split() : 分割字符串
str4 = "www.itdiffer.com"
for str_tmp in str4.split("."):
    print(str_tmp)    #‘www‘ ‘itdiffer‘ ‘com‘


#--------------------------------------------------
# str.strip() : 去掉str左右两边的空格
str5 = " he ha ho "
print(‘去掉前,str5:‘ + str5 + ‘:长度‘ + str(len(str5)))
str5 = str5.strip();
print(str5)
print(‘去掉后,str5:‘ + str5 + ‘:长度‘ + str(len(str5)))


#--------------------------------------------------
# str.lstrip() : 去掉str左边的空格
str5 = " hehe"
print(str5.lstrip())


#--------------------------------------------------
# str.rstrip() : 去掉str右边的空格
str6 = "hehe "
print(str6.rstrip())


#--------------------------------------------------
# str.upper() : 将小写字母,全部转换为大写
str7 = "hello python"
print(str7.upper())


#--------------------------------------------------
# str.lower() : 将大写全部转换为小写
str8 = "HELLO PYTHON"
print(str8.lower())


#--------------------------------------------------
# str.isupper() : 判断当前字符串是否全部为大写
str9 = "hello"
str10 = "HELLO"
print(str(str9.isupper()))        #False
print(str(str10.isupper()))        #True


#--------------------------------------------------
# str.islower() : 判断当前字符串是否全部为小写
str11 = "Hello"
str12 = "python"
print(str(str11.islower()))            #False
print(str(str12.islower()))            #True


#--------------------------------------------------
# str.title() : 将字符串中每个单词的首字母转换为大写(如果字符串全部为大写,则转化结果为:每个单词的首字母大写其他字母小写)
str13 = "hello Pyhton"
str14 = "hello python"
str15 = "HELLO PYTHON"
str13_title = str13.title()            #‘Hello Python‘
str14_title = str14.title()            #‘Hello Python‘
str15_title = str15.title()            #‘Hello Python‘
print(‘str13:{0}‘.format(str13))
print(‘str14:{0}‘.format(str14))
print(‘str15:{0}‘.format(str15))
print(‘str13_title:‘ + str13_title)    #‘str13_title:Hello Pyhton‘
print(‘str14_title:‘ + str14_title)    #‘str14_title:Hello Pyhton‘
print(‘str15_title:‘ + str15_title)    #‘str15_title:Hello Pyhton‘
print(str(str13_title.istitle()))    #True
print(str(str14_title.istitle()))    #True
print(str(str15_title.istitle()))    #True


#--------------------------------------------------
# str.istitle() : 判断每个单词的首字母是否为大写
str16 = "hEllo"
str17 = "World"
str18 = "Hello,World"
str19 = "Hello,world"
print(str(str16.istitle()))    #False
print(str(str17.istitle()))    #True
print(str(str18.istitle()))    #True
print(str(str19.istitle()))    #False


#--------------------------------------------------
# str.capitalize() : 将字符串的第一个字母变为大写
str20 = "hello python"
str20_capitalize = str20.capitalize();
print(str(str20_capitalize))    #‘Hello pythn‘