python全栈（五）基本数据类型，字符串的魔法

#数字比作猎人
num = 123
v = num.bit_length()
print(v)
#字符串：女巫
name1 = 'shizhengwen'
v1 = name1.upper()
print(v1)

name2 = 'laiying'
v2 = name2.upper()
print(v2)

#整形，int
#python3里，122333344，不管数字有多大，都是int类型
#python2里，123344
#长整形，long
#python2里，12233444  long
#========python3 =========
#数字 int，所有的工功能，都放在int 里
#在python3里，1222222222223333333
#字符串 str
#列表   list
#元祖 tuple
#字典 dict 
#布尔值  bool 
按住ctrl 鼠标放在str上会显示所有功能。

- int
   将字符串转换为数字

num = 'a'
v = int (num,base=16)
print(v)

num = 'b'
v = int (num,base=16)
print(v)

当前数字的二进制，至少用N位来表示
age = 5
r = age.bit_length()
print(r)

test = 'alex'
#首字母大写
v= test.capitalize()
print(v)

 #去字符串中寻找，寻找子序列出现的次数

 

test = 'alexalex'
v = test.count('ex')
print(v )


test = 'alexalex'
v = test.count('ex',5)
print(v)

test = 'alexalex'
v = test.count('ex',5,6)
print(v)


#以什么什么结尾
#以什么什么开头

test = 'alex'
v = test.endswith('ex')
print(v)


test = 'alex'
v = test.startswith('ex')
print(v)

#从开始往后找，找到第一个之后，获取其位置

#> 或 >=

 

test = 'alexalex'
v = test.find('ex')
print(v)

test = 'alexalex'
v = test.find('ex',5,7)
print(v)

test = 'alexalex'
v = test.find('ex',5,8)
print(v)

#格式化，将一个字符串中的占位符替换为指它的值

test = 'i am {name}, age{a}'
print(test)
v = test.format(name='alex',a=19)
print(v)

 

test = 'i am {0}, age{1}'
print(test)
v = test.format('alex',19)
print(v)

test = 'i am {name}, age{a}'
v1 = test.format(name='df',a=10)
v2 = test.format_map({'name':'alex','a':19})
print(v1,v2)

#字符串中是否中包含  字母和数字
test = '123'
v =test.isalnum()
print(v)

#expandtabs,继句20
test = 'username\temail\tpassword\nlaiying\tying@q.com\t123\nlaiying\tying@q.com\t123\nlaiying\tying@q.com\t123'
v =test.expandtabs(20)
print(v)

#当前输入是否是数字
test = '123'
v1 = test.isalnum()
v2 = test.isdigit()
print(v1,v2)

test = '二'
v1 = test.isdecimal()
v2 = test.isdigit()
v3 = test.isnumeric()
print(v1,v2,v3)

#字母，数字，下划线： 标识符 def class

a = 'def'
v =a.isidentifier()
print(v)

#是否存在不可显示的字符
# \t 制表符
# \n 换行
test ='oiuted'
v = test.isprintable()
print(v)

test = 'oiut\ned'
v = test.isprintable()
print(v)

test = 'oiut\ted'
v = test.isprintable()
print(v)

#判段是否全部是空格
test = ' '
v = test.isspace()
print(v)

#将字符串中的每一个元素按照指定分隔符进行拼接
test = '你是风儿我是沙'
print(test)
t = ' '
v = t.join(test)
print(v)


test = '你是风儿我是沙'
print(test)
v = ' '.join(test)
print(v)

#设置宽度。并将内容居中
#20代指总长度
#* 空白未知填充，一个字符，可有可无
#v = test.center(20,'中')
#print(v)

test = 'alex'
v = test.ljust(20,'*')
print(v)

test = 'alex'
v = test.rjust(20,'*')
print(v)

test = 'alex'
v = test.zfill(20)
print(v)

#判段是否全部是大小写 和 转换为大小写
test = 'Alex'
v1 = test.islower()
v2 = test.lower()
print(v1,v2)

test = 'Alex'
v1 = test.isupper()
v2 = test.upper()
print(v1,v2)

#去除左右空白
test = ' alex '
v = test.lstrip()
#v = test.rstrip()
#v =test.strip()
print(v)

test = ' alex '
#v = test.lstrip()
v = test.rstrip()
#v =test.strip()
print(v)

test = ' alex '
v = test.lstrip()
#v = test.rstrip()
v =test.strip()
print(v)


移除指定字符
优先最多匹配

test = "xalex"

v = test.rstrip("9lexe")
print(v)

#去除\n \t
test = '\nalex'
#print(test)
v = test.lstrip()
#v = test.rstrip()
#v = test.strip()
print(v)

test = '\nalex'
#print(test)
v = test.lstrip()
#v = test.rstrip()
#v = test.strip()
print(v)

test = '\talex'
print(test)
#v = test.lstrip()
#v = test.rstrip()
#v = test.strip()
#print(v)

test = '\talex'
#print(test)
v = test.lstrip()
#v = test.rstrip()
#v = test.strip()
print(v)

test = 'testasdsddfg'
v = test.partition('s')
print(v)

test = 'testasdsddfg'
#v = test.partition('s')
v = test.rpartition('s')
print(v)

#分割，只能根据，true,false:是否保留换行
test = 'asdfadfasdf\nasdfadfasdf\nasdfadfasdf'
v = test.splitlines(False)
print(v)

test = 'backend 1.1.1.1'
v = test.startswith('ba')
print(v)

#以什么什么开头，以什么什么结尾
test = 'backend 1.1.1.1'
v = test.endswith('1')
print(v)

#大小写转换
test = 'alex'
v = test.swapcase()
print(v)

####################7个基本魔法###################
#join
#split
#find
#strip
#upper
#lower
#replace

test = "alexalexalex"
v = test.replace("ex","bbb")
print(v)

test = "alexalexalex"
v = test.replace("ex","bbb",2)
print(v)

#######################灰魔法####################
索引，下标，获取字符串中的某一个字符

test = "ale"
v = test[1]
print(v)

v = test[0:1] 索引范围，大于等于0，小于1

test = "ale"
v = test[0:1]
print(v)

v = test[0:2] 索引范围，大于等于0，小于2

test = "alex"
v = test[0:2]
print(v)

切片

v = test[0:-1]切片

test = "alex"
v = test[0:-1]
print(v)

#python3: len获取当前字符串中由几个字符组成

test = "郑键文"
v = len(test)
print(v)

#for 循环
for 变量名 in 字符串：
变量名

test = "郑键文妹子有种冲我来"
index = 0
while index < len(test):
    v = test[index]
    print(v)

    index += 1
print("======")

test = "郑键文妹子有种冲我来"
for zjw in test:
    print(zjw)

 
#字符串一但创建，就不能修改。如要修改，就会创建一个新字符串。


# range 帮助创建连续的数字