Python String functions

Generating string variables
str= ' python String function '

String length acquisition: Len (str)
Example: print '%s length=%d '% (Str,len (str))

Connection String
SSTR1 = ' strcat '
SSTR2 = ' Append '
SSTR1 + = SStr2
Print SSTR1

Copy string
#strcpy (SSTR1,SSTR2)
SSTR1 = ' strcpy '
SSTR2 = SStr1
SSTR1 = ' Strcpy2 '
Print SSTR2

Comparing strings
#strcmp (SSTR1,SSTR2)
SSTR1 = ' STRCHR '
SSTR2 = ' Strch '
Print CMP (SSTR1,SSTR2)

# Note that the output of the CMP function is the same as the strcmp of the C language. You can also use "aaa" = = "BBB" to compare strings.

Intercept string

Special Note: The subscript starts at 0; Str[0:3] does not contain a character with subscript 3.
str = ' 0123456789′
Print Str[0:3] #截取第一位到第三位的字符
Print str[:] #截取字符串的全部字符
Print Str[6:] #截取第七个字符到结尾
Print Str[:-3] #截取从头开始到倒数第三个字符之前
Print Str[2] #截取第三个字符
Print Str[-1] #截取倒数第一个字符
Print Str[::-1] #创造一个与原字符串顺序相反的字符串
Print Str[-3:-1] #截取倒数第三位与倒数第一位之前的字符
Print str[-3:] #截取倒数第三位到结尾
Print str[:-5:-3] #逆序截取, what do you mean, you don't understand?

Search and Replace in string :
S.find (substr, [Start, [end]])    #返回S中出现substr的第一个字母的标号, Returns 1 if no substr is in S. The start and end functions are equivalent to searching in s[start:end] for
S.index (substr, [Start, [end]])    #与find (), except when there is no substr in S. Returns a run-time error
S.rfind (substr, [Start, [end]])    #返回S中最后出现的substr的第一个字母的标号, or 1 if there is no substr in S That is to say, the first occurrence of the substr from the right is the first letter of the
S.rindex (substr, [Start, [end]])
S.count (substr, [Start, [end]])      #计算substr在S中出现的次数
S.replace (Oldstr, Newstr, [Count])     #把S中的oldstr替换为newstr, Count is the number of replacements. This is a common form of substitution, and there are some functions to replace the special characters with
S.strip ([chars]) #把S中前后chars中有的字符全部去掉, which can be understood as replacing S chars with none
S.lstrip ([chars])
S.rstrip ([chars])
S.expandtabs ([tabsize])    #把S中的tab字符替换没空格, each tab is replaced by a tabsize space, and the default is 8

splitting and grouping of strings:
S.split ([Sep, [Maxsplit]]) #以sep为分隔符, divide s into a list. Maxsplit represents the number of splits. The default delimiter is a blank character
S.rsplit ([Sep, [Maxsplit]])
S.splitlines ([keepends]) #把S按照行分割符分为一个list, Keepends is a bool value that retains the row delimiter after each row is true.
S.join (seq) #把seq代表的序列-string sequence, connected by s
The mapping of the string, which contains two functions:
The String.maketrans (from, to) #返回一个256个字符组成的翻译表, where the characters from the from are converted to by one by one, so the from and to must be equal in length.
S.translate (Table[,deletechars]) # Use the above function for the post-natal translation table, translate s for translation, and delete the characters in the Deletechars. It is important to note that if S is a Unicode string, then the Deletechars parameter is not supported, and the same functionality can be achieved by translating a character to none. You can also use the functionality of the codecs module to create more powerful translation tables.

Character -Case transformations in strings:
S.lower () #小写
S.upper () #大写
S.swapcase () #大小写互换
S.capitalize () #首字母大写
String.capwords (S) #这是模块中的方法. It separates S with the split () function and then uses the
Capitalize () capitalize the initial letter and merge it with join ()
S.title () #只有首字母大写, the remainder is lowercase, this method is not in the module

String go to space and go to specify character
Go on both sides Space: Str.strip ()
Left space: Str.lstrip ()
Go right Space: Str.rstrip ()
Go to both sides of the string: Str.strip (' d '), corresponding to the Lstrip,rstrip
str= ' python String function '
print '%s strip=%s '% (Str,str.strip ())
str= ' python String function '
print '%s strip=%s '% (Str,str.strip (' d '))

Splits a string by a specified character array: Str.split (")

Stringencoding and decodingThe function:
S.encode ([encoding,[errors]]) # Where encoding can have a variety of values, such as gb2312 GBK gb18030 bz2 zlib Big5 bzse64, etc. are supported. The default value of errors is strict, which means unicodeerror. Possible values are ' ignore ', ' replace ', ' xmlcharrefre
S.encode ([encoding,[errors]]) # Where encoding can have a variety of values, such as gb2312 GBK gb18030 bz2 zlib Big5 bzse64, etc. are supported. The default value for errors is "strict", which means unicodeerror. Possible values are ' ignore ', ' replace ', ' xmlcharrefreplace ', ' backslashreplace ' and all the values registered by Codecs.register_error. This section covers the codecs module, which is not a specific understanding
S.decode ([encoding,[errors]])
Test functions for strings, which are not in the string module and return bool values:
S.startwith (Prefix[,start[,end]) #是否以prefix开头
S.endwith (Suffix[,start[,end]) #以suffix结尾
S.isalnum () #是否全是字母和数字, and has at least one character
S.isalpha () #是否全是字母, and has at least one character
S.isdigit () #是否全是数字, and has at least one character
S.isspace () #是否全是空白字符, and has at least one character
S.islower () #S中的字母是否全是小写
S.isupper () #S中的字母是否便是大写
S.istitle () #S是否是首字母大写的

StringType ConversionsFunctions, these functions are only available in the string module:
String.atoi (S[,base]) #base默认为10, if 0, then s can be 012 or 0x23 This form of string, if it is 16 then s can only be 0x23 or 0x12 this form of string
String.atol (S[,base]) #转成long
String.atof (S[,base]) #转成float

The conversion of a Python string to a number into a string str ()
The string becomes a number string.atoi (S,[,base])//base is the binary cardinality
Floating-point conversion string.atof (s)

The alignment of the string at output :
S.ljust (Width,[fillchar]) #输出width个字符, s left-aligned, the insufficient portion is filled with Fillchar, the default is a space.
S.rjust (Width,[fillchar]) #右对齐
S.center (width, [Fillchar]) #中间对齐
S.zfill (width) #把S变成width长, and right-aligned, less part with 0 complement

Single quotation marks in a string, double quotation marks are escaped with \.

How to convert a string into a number?
int (' 1234 ')

In the string module there are
Import string
>>> a= "12345"
>>> Import String
>>> String.atoi (a)
12345
>>> b= "123.678"
>>> String.atof (b)
123.678

Convert to Long, with String.atol ()

Python String functions