Built-in functions from entry to the autistic Python

A built-in function

eval: type of code execution string
exac: type of code execution string Society

and prohibit the use of eval exac

hash () function is to distinguish between variable data types and data type immutable

# print(hash("123"))
# print(hash(12))
# print(hash(-1))
# print(hash(-10))
# print(hash((2,1)))

# dic = {[1,2,3]:2}
# print(hash([1,2,3]))

help (): View help information

callable (): Check whether the object can be called,

# def func():
#     print(1)
# lst = [1,23,4,]
# print(callable(lst))   # 查看对象是否可调用

int (): string or integer numbers into
float (): converted to floating point
complex (): plural
bin (): Decimal Binary transfer
oct (): Decimal turn octal
hex (): Decimal turn hex
divmod (): calculated result divisor and dividend, the quotient and remainder comprising a Ganso
round (): retention of floating-point decimal places, the number of bits can be set to retain, retain the default integer
pow (): power demand x ** y (when the result of the three parameters of x ** y modulo third parameter)
bytes (): for switching between different coding recommended encode
ord (): Get the current position of the epitope encoded by elemental
chr (): find the corresponding bit number table by elements
repr (): View original ecological data (for programmers)
all (): Summary of the container is determined whether the element are true, returns true
any (): Analyzing container elements have a true, it is True

Anonymous function: line of the function lambda (Bibei)

def func（）：
    print（123）
func（）

grammar:

Function name = lambda parameter: Return value
The name of the anonymous function is called lambda
lambda is a keyword-defined functions, the equivalent def function

Only one data type can return,

面试题：
print ([lambda : i for i in range(5)])
（返回5个内存地址）

print(lst[0]())---结果是4--因为循环最后一次输出是4，调用的全局最后一个就是4
不加后面的小括号就是调用内存地址
加了括号就是调用函数

lst = [lambda X : X+1 for i in range(5)]
print(lst[0](5))
输出结果为：6，返回值是x+1

tu = (lambda : i for i in range(3))
print(tu[0])  #输出错误，不能索引
print（tu）#输出内存地址
print(next(tu))       #一个函数地址
print(next(tu)())     #输出0
print(next(tu)())     #输出1

lst = [lambda : i for i in range(3)]
print(lst[0]())
tu = (lambda : i for i in range(3))
print(next(tu)())
输出结果：
2
0

Body of the function is stored in the code

Generator is stored in the code

- Cause: yield and lead to inconsistent execution result of the function generator

lst = [lambd x:x+5  for i in range(2)]
print([i(2) for i in lst])


解开顺序：
lst = []
for i in range (2):
    lst.append(lambda x :x+5)
new_list
for i in lst:
    print(i)      #两个函数的内存地址
    new_list.append(i(2))
print(new_list)       #输出列表【7，7】

输出结果：【7，7】



lst = (lambda x:x+5  for i in range(2))
print([i(2) for i in lst])



输出结果：【7，7】

lst = （lambda x:x*i  for i in range(2)）
print([i(2) for i in lst])        #【0，2】

lambda == def == keyword
1. lambfa x: x
  - x: shape parameter is a function of the ordinary (location, default), any number can be written, can not write
  - : Behind the ordinary is the return value of the function must be written, no default, must have a return value, you can only write one data type

Two built-in functions (remember all)

Built-in functions

Two dictionaries combined into one:
1. update--- dic2.update(dic1)
2. Broken: - print (dict (** dic1, ** dic2))
3. print (dict ([(1,2), (3,3)])) --- brackets at least one of a digital versatile will not, iterate through the list may be ancestral
4. dict( ** dict1, ** dict2)
set (): The iterables converted into ancestral
sep (): a method for dividing between each element
```
print(1,2,3,sep = "|")
输出结果：1|2|3
```
end: print after the implementation of the end of the statement, the default \ n
```
print(1,2,3,end = "")
print()
输出结果：全部在一行
```
print (): screen output
- flush - Flush

file: file handles, the default display to the screen

print (1,2,3,4,5,file = open ("test","w",encoding="utf-8"))

sum () - sum, the object must be iterative, object elements must be an integer, string type can not be used

print (sum ([1,2,3,1]))
print (sum ([1,2,3,1],100)       #100是起始值，就是从100开始进行取和，指定开始位置的值

abs (): Returns the absolute value - converted into a positive number, whether you are not negative
dir (): View the current object has any way

zip (): the fastener, when the length is inconsistent iterables choose the shortest merge may be a plurality of

面试题：
list1 =[1,2,3,4]
lst2 = ["alex","wusir","meet"]
print(list(zip(lst1,lst2)))

输出结果：[(1,"alex"),(2,"wusir"),(3,"meet")]

print(dict(zip(lst1,lst2))) #返回一个字典
输出结果：{1:"alex",2:"wusir",3:"meet"}

format (): format conversion

Alignment

print(format("alex",">20"))  #右对齐
print(format("alex","<20"))  #左对齐
print(format("alex","^20"))  #居中

Hexadecimal conversion

print(format(10,"b"))        #十进制转二进制
print(format(10,"08b"))      #不够就补0

print (format(10,"08o"))     #oct,八进制
print (format(10,"08x"))     #hex，十六进制

print(format(0b1010,"d"))    #二进制转十进制

reversed (): an inverted sequence, flipped sequence returns an iterator

l = reversed('你好')  # l 获取到的是一个生成器
print(list(l))
ret = reversed([1, 4, 3, 7, 9])
print(list(ret))  # [9, 7, 3, 4, 1]