Introduction to python basic data types

Operator

1. Arithmetic operations:

2. Comparison operations:

3. Assignment operation:

4. Logical operation:

5. Member operation:

Basic data types

1. Number

int (integer type)

On a 32-bit machine, the number of digits in an integer It is 32 bits, and the value range is -2**31~2**31-1, that is, -2147483648~2147483647
On a 64-bit system, the number of digits in the integer is 64 bits, and the value range is -2* *63～2**63-1, that is -9223372036854775808～9223372036854775807

##2, Boolean value

True or False

　1 Or 0

3, string

"hello world"

Common functions of strings:

Remove whitespace

Separation

Length

Index

Slice

4. List

Create a list:

name_list = ['alex', 'seven', 'eric']

or

name_list = list(['alex', 'seven', 'eric'])

##Basic operations:

Index

Slice

Append

Delete

Length

Slice

Loop

Contains

##5, Yuanzu

Create Yuanzu:

ages = (11, 22, 33, 44, 55)

or

ages = tuple((11, 22, 33, 44, 55))

Basic operations:

Index

Slice

Loop

Length

Contains

6, dictionary (unordered)

Create dictionary:

person = {"name": "mr.wu" , 'age': 18}

or

person = dict({"name": "mr.wu", 'age': 18})

Common operations:

Index

Add

Delete

Key, value, key-value pair

Loop

Length

PS: loop, range, continue and break

Others

1. for loop

The user loops the contents of the iterable object in order,

PS: break, continue

li = [11,22,33,44]

for item in li:

print item

2, enumrate

Add serial number to iterable object

li = [11,22,33 ]

for k,v in enumerate(li, 1):

print(k,v)

3, range and xrange

Specify range , generate the specified number

print range(1, 10)

# Result: [1, 2, 3, 4, 5, 6, 7, 8, 9]

print range(1, 10, 2)

# Result: [1, 3, 5, 7, 9]

print range(30, 0, -2)

# Result: [30, 28, 26, 24, 22, 20, 18, 16, 14, 12, 10, 8, 6, 4, 2]　

Exercise questions

1. Element classification

has the following value set [11,22,33,44,55,66,77,88,99,90... ], save all values ​​greater than 66 to the first key of the dictionary, and save values ​​less than 66 to the value of the second key.

That is: {'k1': all values ​​greater than 66, 'k2': all values ​​less than 66}

2. Search

Find the elements in the list and remove each elements, and finds all elements starting with a or A and ending with c.

li = ["alec", " aric", "Alex", "Tony", "rain"]

tu = ("alec", " aric", "Alex", "Tony", "rain")

dic = {'k1': "alex", 'k2': ' aric', "k3": "Alex", "k4": "Tony"}

3. Output the product list, the user enters the serial number, and the product selected by the user is displayed

Product li = ["Mobile phone", "Computer", 'Mouse pad', ' Yacht']

4. Shopping cart

Functional requirements:

Requires the user to enter total assets, for example: 2000

display The product list allows users to select products based on serial numbers and add them to the shopping cart

for purchase. If the total number of products is greater than the total assets, it will prompt that the account balance is insufficient. Otherwise, the purchase is successful.

Additional: Can be recharged, a certain product can be removed from the shopping cart

goods = [

{"name": "Computer", "price" : 1999},

{"name": "mouse", "price": 10},

{"name": "yacht", "price": 20},

{"name": "Beauty", "price": 998},

]

5. User interaction, displaying the selection of three-level linkage between provinces, cities and counties

dic = {

"Hebei": {

"Shijiazhuang": ["Luquan", "Gaocheng", "Yuanshi"],

"Handan": ["Yongnian", "Shexian", "Cixian"],

}

"Henan": {

...

}

"Shanxi": {

 ...

}

}

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