Python Basic data type

List of articles

• Python Basic data type
• • • • • • Multiple variable assignments
    • Standard data type
    • • 1. Numeric type （number）：
      • • • Digital type conversion ：
          • Hexadecimal conversion ：
      • 2. String type (string)：
      • 3. List the type （list):
      • 4. Tuples （tuple):

Python Variables of do not need to be declared , Each variable must be assigned a value before use , Variables can only be created after assignment . Equal sign (=) It is used to assign values to variables , The format is ： Variable name = Values stored in variables .

Multiple variable assignments

Python It is allowed to assign values to multiple variables at the same time , for example ：

a = b = c = 1

Create an integer object , The value is 1, From the back to the front , Multiple variables are given the same value

Standard data type

Python There are six standard data types in ：

• number：( Numbers )
• string：( character string )
• list：( list )
• tuple：( Tuples )
• set:( aggregate )
• dictionary:( Dictionaries )

Python Of the six standard data types ：

• Immutable data types ：number( Numbers )、string( character string )、tuple( Tuples )
• Variable data type ：list( list )、dictionary( Dictionaries )、set( aggregate )

1. Numeric type （number）：

(1).int integer ：Python Can handle integers of any size .
(2).flolat floating-point ： It is composed of integral part and decimal part , To approximate or round without being able to calculate accurately .
(3)bool Boolean type ： Used as a logical judgment , The value of a variable is only true （True） And fake （False）,
(4)complex The plural ： It is composed of a real number and an imaginary number , Expressed as ：x+yj, A complex number is a pair of ordered floating-point numbers （x,y）, among x Is the real part , Is the imaginary part .

Digital type conversion ：

We can convert numeric types through built-in functions .

• take int Convert to bool,0 convert to False, Not 0 convert to True.

print(bool(a))# a For integer numbers 

• take bool Convert to int,False convert to 0,True convert to 1.

print(int(a))# a by False or True

• take float Convert to int

print(int(a))# a Is a floating-point number 

• take int Convert to float

print(float(a))# a For integer numbers 

• take bool Convert to float

print(float(a))# a by False or True

• take float Convert to bool

print(bool(a))# a Is a floating-point number 

Hexadecimal conversion ：

• hex(i) take 10 Hexadecimal numbers are converted to 16 Base number .
• oct(i) take 10 Hexadecimal numbers are converted to 8 Base number .
• bin(i) take 10 Hexadecimal numbers are converted to 2 Base number .
• use int() Convert other base numbers to 10 Base number .

Be careful ： Switching , If there are other useless characters, an error will be reported , Plus and minus signs make sense .

2. String type (string)：

• Python The self string in is used as ' And double quotes " Cover up , Also use a backslash \ Escapes special characters .
• With 0 Start index for ,-1 Index the beginning of the flashback .
• + Is the concatenator of a string ,* Means to copy the current string , The number that follows is the number of copies .
• python String cannot be changed
  Be careful ：python There is no separate character type in , A character is a string of length one .

3. List the type （list):

• The list is written in [] Between , A comma separated list of elements .
• List can complete the data structure implementation of most collection classes . The types of elements in the list can be different , It contains numbers 、 Strings and even lists （ nesting ）
• Just like a string , Lists can also be indexed and intercepted , After the list is intercepted, a new list is returned .
• Index from 0 Start ,-1 Is the index value at the end .
• + Is a list connector * Is a repeat operation , The elements in the list can be changed .
• list yes python The most commonly used data type in .

4. Tuples （tuple):

Tuples are similar to lists , The difference is that elements of tuples cannot be modified , Tuples are written in parentheses () in , Use commas... Between elements , separate .
Tuples are similar to strings , Can be indexed and indexed from 0 Start ,-1 Is the beginning of the end . Although tuples are immutable , But it can contain mutable objects . Tuples also use + To splice .
Be careful ：string,list,tuple All belong to sequebce( Sequence ) Of .