01-common operations on strings in python, 01-python strings

01-common operations on strings in python, 01-python strings

(1) find

Check whether str is included in myStr. If yes, the initial index value is returned. Otherwise,-1 is returned.

In [1]: myStr = "hello world tairan and tairanCity."In [2]: str = "tairan"In [3]: myStr.find(str)Out[3]: 12

In [7]: str = "helo"

In [8]: myStr.find(str)
Out[8]: -1

(2) index

Search for indexes.

In [9]: myStr = "hello world tairan and tairanCity" In [10]: myStr. find ("world") Out [10]: 6In [11]: myStr. find ("tairan") Out [11]: 12In [12]: myStr. rfind ("tairan") Out [12]: 23 # rfind indicates a query from right to left.

(3) count

Returns the number of times that str appears in myStr between start and end.

In [13]: myStrOut[13]: 'hello world tairan and tairanCity'In [14]: myStr.count("hello")Out[14]: 1In [15]: myStr.count("tairan")Out[15]: 2

(4) replace

Replace 'str' in myStr with new_str. If 'Count' is specified, it cannot exceed 'Count.

In [16]: myStrOut [16]: 'Hello world tairan and tairancity' In [17]: myStr. replace ("hello", "nihao") Out [17]: 'nihao world tairan and tairancity' In [18]: myStr. replace ("tairan", "TaiRan") Out [18]: 'Hello world TaiRan and tairancity' In [20]: myStr. replace ("tairan", "Tairan", 1) # If count is specified, replace the value cannot exceed count times Out [20]: 'Hello world Tairan and tairanCity'

(5) split

Cut, which uses str as the separator. If maxsplit has a specified value, only the maxcompute strings are separated.

In [21]: myStrOut [21]: 'Hello world tairan and tairancity' In [22]: str = "" In [23]: myStr. split (str) Out [23]: ['hello', 'World', 'tairance', 'and', 'tairancity']

In [24]: myStr. split (str, 2) # specify count as 2
Out [24]: ['hello', 'World', 'tairan and tairancity']

(6) capitalize

The first character of the string is capitalized.

In [25]: myStrOut[25]: 'hello world tairan and tairanCity'In [26]: myStr.capitalize()Out[26]: 'Hello world tairan and tairancity'

(7) title

The first letter of each word in the string is capitalized.

In [27]: myStrOut[27]: 'hello world tairan and tairanCity'In [28]: myStr.title()Out[28]: 'Hello World Tairan And Tairancity'

(8) startswith

Checks whether the string starts with obj. If yes, True is returned. Otherwise, False is returned.

In [29]: myStrOut[29]: 'hello world tairan and tairanCity'In [30]: myStr.startswith("hello")Out[30]: TrueIn [32]: myStr.startswith("helo")Out[32]: False

(9) enddswith

Check whether the string has ended with obj. If yes, True is returned. Otherwise, False is returned.

In [33]: myStrOut[33]: 'hello world tairan and tairanCity'In [34]: myStr.endswith("ty")Out[34]: TrueIn [35]: myStr.endswith("txt")Out[35]: False

(10) lower

Converts all uppercase characters in mystr1.

In [36]: myStr1 = "HELLO WORLD TAIRAN AND TAIRANCITY"In [37]: myStr1.lower()Out[37]: 'hello world tairan and tairancity'

(11) upeer

Converts all lowercase characters in myStr to uppercase.

In [38]: myStrOut[38]: 'hello world tairan and tairanCity'In [39]: myStr.upper()Out[39]: 'HELLO WORLD TAIRAN AND TAIRANCITY'

(12) ljust

Returns a new string with the left alignment of the original string and filled with spaces to the width.

In [40]: str = "hello"In [41]: str.ljust(10)Out[41]: 'hello     '

(13) Just UST

Returns the right of an original string.

In [42]: strOut[42]: 'hello'In [43]: str.rjust(10)Out[43]: '     hello'

(14) center

Returns a new string with the original character centered and filled with spaces to the width.

In [45]: str.center(10)Out[45]: '  hello   '

(15) lstrip

Delete the white space characters on the left of myStr.

In [47]: myStr = "       hello"In [48]: myStr.lstrip()Out[48]: 'hello'

(16) rstrip

Delete the white space characters on the Right of myStr.

In [49]: myStr = "hello         "In [50]: myStr.rstrip()Out[50]: 'hello'

(17) strip

Delete white spaces at both ends of the myStr string.

In [51]: myStr = "    hello       "In [52]: myStr.strip()Out[52]: 'hello'

(18) partition

Split myStr into three parts: str before, str, and str.

In [53]: myStr = "hello world tairan and tairanCity. "In [54]: str =" tairan "In [55]: myStr. partition (str) Out [55]: ('Hello world', 'tairanc', 'and tairanCity. ') # The returned result is a tuples with spaces In [56]: myStr. rpartition (str) Out [56]: ('Hello world tairan and ', 'tairan', 'city. ') # rpartition indicates searching from right to left

(19) splitlines

Returns a list containing rows as elements.

In [57]: myStr = "hello\nworld"In [58]: print(myStr)helloworldIn [59]: myStr.splitlines()Out[59]: ['hello', 'world']

(20) isalpha

If all characters in myStr are letters, True is returned; otherwise, False is returned.

In [61]: myStrOut[61]: 'danjk'In [62]: myStr.isalpha()Out[62]: TrueIn [63]: myStr1 = "1244"In [64]: myStr1.isalpha()Out[64]: False

(21) isdigit

If myStr only contains numbers, True is returned; otherwise, False is returned.

In [66]: myStr = "213131"In [67]: myStr.isdigit()Out[67]: TrueIn [68]: myStr = "dmakd"In [69]: myStr.isdigit()Out[69]: False

(22) isalnum

Returns True if the string is a character or number; otherwise, returns False.

In [70]: myStr = "21da2"In [71]: myStr.isalnum()Out[71]: TrueIn [72]: myStr = "2112123"In [73]: myStr.isalnum()Out[73]: True

(23) isspace

If the string contains at least one letter and all characters are spaces, True is returned. Otherwise, False is returned.

In [74]: myStr = "       "In [75]: myStr.isspace()Out[75]: TrueIn [76]: myStr = "   dad       "In [77]: myStr.isspace()Out[77]: False

(23) join

Insert str after each character in myStr to construct a new string.

In [78]: str = " "In [79]: myStr = ["my","name","is","xiaoyafei"]In [80]: str.join(myStr)Out[80]: 'my name is xiaoyafei'

In [81]: str = "_"In [82]: str.join(myStr)Out[82]: 'my_name_is_xiaoyafei'