Python variable type

Variable assignment

Python variables do not need to type an assignment statement.

Each variable is created in memory, including all logos, names and data of variable information.

Each variable must be assigned before use, variable assignment after the variable will be created.

Equal sign (=) is used to assign values ​​to variables.

Equal sign (=) operator on the left is a variable name, an equal sign (=) operator on the right is the value stored in the variable. E.g:

#!/usr/bin/python
# -*- coding: UTF-8 -*-

counter = 100 # 赋值整型变量
miles = 1000.0 # 浮点型
name = "John" # 字符串

print counter
print miles
print name

Running instance >> Download

The above example, 100,1000.0 and "John" are assigned to the counter, miles, name variable.

The above program will output the following results:

100
1000.0
John

A plurality of variable assignment

Python allows you to assign multiple variables simultaneously. E.g:

The above examples, create an Integer object, and a value of 1, three variables are assigned to the same memory space.

You can also specify multiple variables into multiple objects. E.g:

The above examples, two integer objects 1 and 2 is assigned to the variable a and b, string object "john" is assigned to the variable c.

Standard data types

Stored data can be a variety of types in memory.

For example, person.s age as a value stored in his or her address is stored in alphanumeric characters.

Python has some standard used to define the type of operation, and they may be for each of them the storage method.

Python has five standard data types:

• Numbers (Digital)
• String (String)
• List (list)
• Tuple (tuple)
• Dictionary (dictionary)

Python figures

Numeric data type is used to store values.

They are immutable data types, which means changing the numeric data type will be assigned a new object.

When you specify a value, Number object is created:

You can also use the del statement to delete some object.

del statement syntax is:

You can refer to by using the del statement to delete single or multiple objects. E.g:

Python supports four different types of figures:

• int (a signed integer)
• long (long integers [can also represent octal and hexadecimal])
• float (float)
• complex (complex)

Some examples of numeric types:

• You can also use a long integer lowercase "L", but it is recommended that you use an uppercase "L", to avoid the number "1" confusion. Python uses "L" to display the long integer.
• Python also supports complex numbers, complex numbers by the real and imaginary parts, you can use a + bj, or complex (a, b) that the real part and an imaginary part b is a floating-point

Python strings

String or strings (String) is a string of characters consists of numbers, letters, underscores thereof.

Usually referred to as:

It is a programming language indicates the data type of text.

Python string list are two kinds of values ​​in order:

• From left to right index defaults to zero, the maximum range is less string length 1
• From right to left starting at -1 index default, the maximum range is the beginning of a string

If you want to get some real substring, you can use the variables [under the header: Last subscript], you can intercept the corresponding string, where the subscript 0 is measured from the beginning, which can be positive or negative, under mark can be empty means to take the head or tail.

such as:

s [1: 5] is the result of love.

When using a colon-separated strings, python returns a new object that contains the results in order to offset the contents of this continuous identification, beginning on the left is included under the border.

The above results include the s [1] the value of l, the maximum range is not taken to include the border is s [5] the value of p.

Plus sign (+) is the string concatenation operator, the asterisk (*) is repeated operations. The following examples:

Examples of the above output:

Python list

You can complete the list data structure to achieve most of the collection class. It supports characters, numbers, strings and even contains a list (called nesting).

List with a [] logo. Python is the most common type of complex data. See the code to understand.

List segmentation deserve to be used in variable [under the header: Last subscript], you can intercept the appropriate list, from left to right by default index of 0, default index from right to left starting at -1, the subscript may blank means to take the head or tail.

Plus sign (+) is a list of the concatenation operator, the asterisk (*) is repeated operations. The following examples:

Examples of the above output:

Python tuple

Tuple is another data type, similar to the List (list).

Tuple with "()" logo. Internal elements separated by commas. But not the second tuple assignment, equivalent to read-only list.

Examples of the above output:

The following is a tuple invalid because tuples are not allowed to update. The list is updated to allow:

Python element dictionary

Dictionary (dictionary) is in addition to python than among the list of the most flexible type of built-in data structures. The list is ordered binding objects, dictionaries are unordered collections of objects.

The difference between the two is: among the elements of the dictionary is accessed by a key, rather than through an offset access.

Dictionary use "{}" logo. Dictionary by the index (key) and its corresponding value value components.

The output is:

Python data type conversion

Sometimes, we need to built-in data type conversion, data type conversion, you only need to type the data as a function name.

Several built-in functions can perform conversions between data types. These functions return a new object that represents the converted value.