一.字符串基础语法

name = "yao"
Year = 1993
print( name + str(Year))
>>yao1993

print(ord("a"))
print(chr(97))
>>97
>>a

print(dir(str))
>>

[‘__add__‘, ‘__class__‘, ‘__contains__‘, ‘__delattr__‘, ‘__dir__‘, ‘__doc__‘, ‘__eq__‘, ‘__format__‘, ‘__ge__‘, ‘__getattribute__‘, ‘__getitem__‘, ‘__getnewargs__‘, ‘__gt__‘, ‘__hash__‘, ‘__init__‘, ‘__init_subclass__‘, ‘__iter__‘, ‘__le__‘, ‘__len__‘, ‘__lt__‘, ‘__mod__‘, ‘__mul__‘, ‘__ne__‘, ‘__new__‘, ‘__reduce__‘, ‘__reduce_ex__‘, ‘__repr__‘, ‘__rmod__‘, ‘__rmul__‘, ‘__setattr__‘, ‘__sizeof__‘, ‘__str__‘, ‘__subclasshook__‘, ‘capitalize‘, ‘casefold‘, ‘center‘, ‘count‘, ‘encode‘, ‘endswith‘, ‘expandtabs‘, ‘find‘, ‘format‘, ‘format_map‘, ‘index‘, ‘isalnum‘, ‘isalpha‘, ‘isascii‘, ‘isdecimal‘, ‘isdigit‘, ‘isidentifier‘, ‘islower‘, ‘isnumeric‘, ‘isprintable‘, ‘isspace‘, ‘istitle‘, ‘isupper‘, ‘join‘, ‘ljust‘, ‘lower‘, ‘lstrip‘, ‘maketrans‘, ‘partition‘, ‘replace‘, ‘rfind‘, ‘rindex‘, ‘rjust‘, ‘rpartition‘, ‘rsplit‘, ‘rstrip‘, ‘split‘, ‘splitlines‘, ‘startswith‘, ‘strip‘, ‘swapcase‘, ‘title‘, ‘translate‘, ‘upper‘, ‘zfill‘]

name.swapcase() #小写变大写，大写变小写

name.capitalize() #首字母大写

name.upper()      #全部大写

name.lower()      #全部小写

name.title()        #首字母全部大写

name.find("n")  #找到“n”所在的位置，从0开始
name.index("n")#检索元素在变量中的位置，从0开始

print (name.count("n"))

print(len(name))

pow(x,y)=x**y=x的y次方

print(bas(-2))
>>2

print(5%3)
>>2
print(divmod(5,3))#取商和余数
(1,2)

print(max(1,2,3))#最大
>>3

int(x) #将x变为整数，舍弃小数部分
float(x)#将x变为浮点数，增加小数部分
complex(x)#将x变为复数，增加虚数部分

x=5.453
print(round(x,2))#round(x,d) d是保留几位小数

name="\nYao\n"
print(name.lstrip())#去掉左边的换行符或者空格
print(name.rstrip())#去掉右边的换行符
print(name.strip()) #去掉全部换行符

print(‘ag12‘.isalnum())#判断是否为数字和字母组成
print(‘ag‘.isalpha())#判断是否只为字母
print(‘2‘.isdigit())#判断是否只为整数
print(‘1‘.isdecimal())#判断是否为十进制
print(‘a-1R‘.isidentifier())#判断是否为一个合格的标识符或变量名,即不能有特殊字符，只能有整数和字母
print(‘My Name‘.istitle())#判断所有字母是否大写

print(name.center(50,‘%‘)) #以50为宽度，不足用‘%’填充，name在中间
print(name.ljust(50,‘%‘))  #不足用%补，在后面补

print(name. rjust(50,‘%‘))  #不足用%补，在前面补

p = str.maketrans(‘abc‘,‘123‘)#用p制造替换规则，
print(‘adbce‘.translate(p))     #然后用translate进行替换

print(‘alexa‘.replace(‘a‘,‘A‘,1))#1表示替换几个

1.split  #返回列表
    b=‘www.baidu.com‘
    c=b.split(‘.‘)
    print(c)
    >>[‘www‘, ‘baidu‘, ‘com‘]
2.join
    c=[‘www‘, ‘baidu‘, ‘com‘]
    d=‘*‘.join(c)
    print(d)
    >>www*baidu*com

a = [7,2,4,3,1]
a.sort()#默认从小到大，（reverse = True）从大到小


print(a)

print(sorted(a))#临时排序
print(a)
>>[1, 2, 3, 4, 7]

  >>[7, 2, 4, 3, 1]

a.reverse()#反转列表

Name = [‘xiao‘,‘da‘,‘max‘]
Name[0] = ‘You‘
print(Name)
>>[‘You‘, ‘da‘, ‘max‘]

#插入元素
Name = [‘xiao‘,‘da‘,‘max‘]
Name.insert(0,‘Apple‘)
print(Name)
>>[‘Apple‘, ‘xiao‘, ‘da‘, ‘max‘]
#添加元素
Name.append(‘blue‘)
 

Name = [‘xiao‘,‘da‘,‘max‘]
del Name[0]#根据索引删除
print(Name)

print(Name.pop())#可删除列表末尾的元素，并让你能够使用删除的元素
#也可以添加索引 pop(1)
print(Name)
>>max
>>[‘xiao‘, ‘da‘]

Name.remove(‘da‘)#不知道位置，可以用remove()