Common operations for data type &STR

1. Digital Int.

The numbers are mainly used for computational purposes.

2. String str

Index and slice of a string

Index is subscript, that is, the elements of a string start with the first, the initial index is 0 and so on

s= (' ABCDEFG ') print (s[0])    #  Aprint (s[1])    #  B

A slice is a segment of a string that is truncated by an index (index start: Index end: Step), forming a new string (in principle Gu Tou regardless of the tail).

s= (' ABCDEFG ') print (S[0:3])    #  Abcprint (s[1:])      #  Bcdefgprint (S[1:6:2])   #bdfprint (S[-1::-2])    #步长-2 Geca

3. Boolean bool

There are two types of Boolean values: True,false. is the correct condition of the reaction.

4. List of lists

One of the underlying data types in Python is enclosed in [], with each element separated by commas, and he can hold a variety of data types.

5. Yuan zu Tupe

Ganso is also known as a read-only list, where data can be queried but cannot be changed.

6. Dictionary Dict

Dictionaries are used to store large amounts of relational data, enclosed in {}.

Conversion of data types:

1. Conversion string of character and number to digital   i.e.   int (str) condition:        Note:   str must be a numeric string number to convert to string   That is, str (int ) Condition 2. Converts a Boolean value to a number to a Boolean value:   when the number is 0               Boolean value of false                                                When numbers are non-0          Boolean value True      Boolean converted to digital:   when the Boolean value is true    The number can be converted to 1                                               when the Boolean value is false , the number can be converted to 03. Boolean and String conversions: for example: s= ('   ')   string content is empty, Boolean value false            s= (' abc ')   string content is not empty, the Boolean value true  the operation of the string: Example: s= ("ADFJFFJFA" )

(1) First letter capitalization

s= (' ADFJFFJFA ') s1=s.capitalize () print (S1)

Adfjffjfa

(2) Case reversal

s= (' ADFJFFJFA ') s1=s.swapcase () print (S1)

Adfjffjfa

(3) All caps

s= (' ADFJFFJFA ') S1=s.upper () print (S1)     #结果为ADFJFFJFA

(4) Change all lowercase

s= (' ADFJFFJFA ') S1=s.lower () print (S1)     #结果为adfjffjfa

(5) Capitalize the first letter of each separated element

Cases

s= (' ADFJ ff JFA ') S1=s.title () print (S1)     #结果为ADFJ FF JFA

(6) Number of occurrences of counting elements

s= (' ADFJ ff JFA ') S1=s.count (' F ') print (S1)     #结果为3

(7) Delete

Strip (): The default is to remove the leading and trailing spaces that are used to remove strings, or to delete characters

Lstrip (): Delete the character to the left of the string

Rstrip (): Delete character to the right of the string

(8) Index Search by element

Find: Returns 1 if the corresponding index is not found

The default here is to return to the location of the first one found.

s= (' Keep your self ') s1=s.find (' E ') print (S1)     #结果为1

Index: Error if no corresponding index is found

s= (' Keep your self ') s1=s.index (' E ') print (S1)     #结果为1

(9) Judgment on what to start/end with: Startwish, endwish

s= (' Keep your self ') s1=s.startwith (' ka ') print (S1)     #结果为False

Endwish

(10) Solving the number of characters in a string

s= (' Keep your self ') print (Len (s))                   #结果为14, spaces are also counted characters        

(11) Split: Split to break a string into a list

s= (' Keep your self ') s1=s.split (' E ') print (S1)     #结果为 [' k ', ' ', ' p ' your s ', ' LF ']

(12) Determine if the character in the string is a number and the return value is a bool value.

S= (' a ') S1=s.isdigit () print (S1)    #结果是False

(13) Fill Center (length, character to fill)

s= "ABC" S1=s.center (5, ' * ') print (S1) results are *abc*

Common operations for data type &STR