7.30 python basis of data types
Numeric (int)
Integer
It can be numerically expressed. Age, number ......
definition
age = 18 # age = int(18)
tel = 18855480890use
Addition, subtraction, logical judgment ......
Float (float)
It represents increased body weight, salary ......
definition
height = 1.88 # height = float(height)
weight = 110
salary = 18.5use
Addition, subtraction, logical judgment ......
String
Indicate the name, sex ......
definition
String is a string of characters are strung together, wrapped in single quotes, or three double quotation marks a string of characters. Note that: three characters in quotation marks can newline, and characters in single or double quotation marks can not.
name = 'wzh' # name = str(wzh)
gender = "male"
id1 = '''adc
def'''
id2 = """xyz
opq"""use
+ Only string, and the logical comparison *
String concatenation, namely re-apply for a small space a copy of the two strings are then spliced. Instead you YY of the variable value in a small space inside the copy to another variable of a small space, and then stitching.
s = "nick's hand"
x = ' laji'
print(s+x) # nick's hand laji
print('nick '*3) # nick nick nick
print('nick' == 'shabi') # False
print('n' in 'nick') # True
print('ck' not in 'nick') # FalseString index
Each string has an index from zero in ascending order from left to right, or right to left in descending order from -1
s = 'nick shabi'
0123456789
-10-9...-2-1 With the index, you can follow the string value index
s = 'nick shabi'
s[0] # n
s[-2] # b
s[:] # nick shabi
s[:4] # nick 顾头不顾尾，末位k取到索引4
s[-5:] # shabi
s[:8:2] # nc h 步长位2，按步长间隔取值
s[::-1] # ibahs kcin 倒序取值List
If you now give us a demand, we need a hobby out of this man, seemingly with our current knowledge can not start. This time you have to change our strategy, we can for ways to store a person's hobby - list.
effect
Storing a plurality of values, such as a plurality of girlfriend, a plurality of hobbies.
definition
Any type of value are separated by a comma within [].
hobby = 'read'
hobby_list = [hobby, 'run', 'girl'] # 可存取任意类型的数据
print(hobby_list) # ['read', 'run', 'girl']use
Similarly the string, but also a list of index values, index values may be utilized
hobby_list = ['read', 'run', ['girl_name', 18, 'shanghai']]
hobby_list[0] # read
hobby_list[2][1] # 18dictionary
effect
A plurality of values used to access, in accordance with key: value of the stored-value mode, may not take the time to go to the index value by the key, key has a function of descriptive value. Store a variety of types of data and more data when you can use a dictionary.
definition
{} In the plurality of elements separated by commas, each element is key: value format, the format in which the value is an arbitrary data type, since the key has a function descriptive, the key is usually a string type.
user_info = {'name': 'nick', 'gender': 'male', 'age': 19,
'company_info': ['oldboy', 'shanghai', 50]}
use
Dictionary values acquired value is a value obtained by taking the key value
user_info = {'name': 'nick', 'gender': 'male', 'age': 19,
'company_info': ['oldboy', 'shanghai', 50]}
user_info['name'] # nick
user_info['company_info'] # ['oldboy', 'shanghai', 50]
user_info['company_info'][1] # shanghai
Add key-value pairs in the dictionary
user_info = {'name': 'nick', 'gender': 'male', 'age': 19,
'company_info': ['oldboy', 'shanghai', 50]}
user_info['weight'] = 110
user_info['height'] = 188
for i in user_info.items():
print(i)
# ('name', 'nick')
# ('gender', 'male')
# ('age', 19)
# ('company_info', ['oldboy', 'shanghai', 50])
# ('weight', 110)
# ('height', 188)
Boolean value (bool)
effect
Conditions for determination result
definition
True, False usually not directly quoted, required logic operation result obtained.
use
print(bool(0)) # False
print(bool('nick')) # True
print(bool(1 > 2)) # False
print(bool(1 == 1)) # True
Note: Python values of all data types comes Boolean value. So much data types only need to remember only 0, None, an empty, False Boolean value is False, the rest to True.
unzip
Decompression is actually unpack the more value out one-off
name_list = ['nick', 'egon', 'jason', ]
x, y, z = name_list
print(x, y, z) # nick egon jason
Sometimes we decompress values may be we do not want, you can use an underscore
name_list = ['nick', 'egon', 'jason', 'tank']
x, y, z, a = name_list
print(x,y,z,a) # nick egon jason tank
x, _, z, _ = name_list
print(x,z) # nick jason
x,*_,y = name_list
print(x,y) # nick tank
Dictionary is also possible, but dictionaries decompression is key.
dic = {'name':'sss','age':123,'height':12312344}
for k,v in lis.items():
print(k,v)
# name sss
# age 123
# height 12312344
Interaction with the user
Accept the value entered by the user input, the user is interacting with the
id = 'wzh'
psw = '123'
id_info = input("请输入id：") # 与用户交互，引导用户输入id,psw
psw_info = input("请输入password：")
if id_info == id and psw_info == psw:
print("欢迎登陆！")