Defined functions

def 函数名（等同于变量名）:
    '''对函数（工具）的描述信息'''
    代码块

example:

def guess():
    '''给定两个数，打印较大的数'''
    x=20
    y=30
    if x>y:
        print(x)
     else:
        print(y)
print(guess.__doc__)#打印注释

The characteristic function is defined: function definition procedure, only detect syntax, the code is not performed. Call phase, it will execute the code.

Three forms defined functions #

Empty function

def shopping():
    pass

There are function parameters

def guess(x,y):
    '''给定两个数，打印较大的数'''
    if x>y:
        print(x)
     else:
        print(y)
print(guess.__doc__)#打印注释
guess(10,20)

No-argument function

def guess():
    '''给定两个数，打印较大的数'''
    x=20
    y=30
    if x>y:
        print(x)
     else:
        print(y)
print(guess.__doc__)#打印注释

Call functions

Call: function name ()

guess()# 调用
print(guess)#函数的内存地址

Function's return value

Return Value: returns a value (all data types)

def guess():
    '''给定两个数，打印较大的数'''
    x=20
    y=30
    if x>y:
        return x
     else:
        return y
num=guess()
print(num)

return characteristics:

1.return returns a return value, if no return value, return None

2. There is no return, default return None

3.return function terminates, the following code is not running, when assuming a plurality of return, it will run to the end of the first, the second will not run.

4.return separated by commas, you can return multiple values, return values accepted as a tuple.

Function parameters

Katachisan

The product of stage defined function having arguments is accepted as having a descriptive sense

Location parameter

Accepts values from left to right argument

The default parameter

1. If you do not give a value, the default value; if the value when called by value, use pass

2. The default parameter must be placed behind the position parameter

Arguments

The product call stage, pass a particular parameter value, according to a specific value (so-bit data type can)

Argument position

From left to right position to pass parameter values correspond, parameter number, the number of arguments must.

Keyword argument

1. The position argument must be written before the keyword arguments.

2. The name of the parameter to pass parameter values (usage is substantially 0) - "parameter function is generally 0-3, so as not more than three.

Vararg

The variable length parameter

* Lt, all pass over all arguments received and stored in the form of a tuple

def min_10(a, b, c, *lt):  # *lt，把所有传过来的实参全部接收，并且以元组的形式存储
    print(lt)#(4, 5, 6, 7, -1, 9, 10, 11, 12, 13, 1, 1, 1, 1, 1, 1, 1, 11, 1)
    a, b, c, d, e, f, g, h, i, j, *_ = lt
    print(_)#[1, 1, 1, 1, 1, 1, 1, 11, 1]
res = min_10(1, 2, 3, 4, 5, 6, 7, -1, 9, 10, 11, 12, 13, 1, 1, 1, 1, 1, 1, 1, 11,
             1, )  # *,相当于做了解压缩，也就是把lt内的元素一个一个取出来传给形参
print(res)

Variable-length argument

* Equivalent to do decompression, i.e. the elements within lt taken out one by one passed parameter

def min_10(a, b, c, d, e, f, g, h, i, j):
    print(a, b, c, d, e, f, g, h, i, j)#1 2 3 4 5 6 7 8 9 10
lt = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
res = min_10(*lt)  # *,相当于做了解压缩，也就是把lt内的元素一个一个取出来传给形参
print(res)

day 010 summary