[Python] Function basic

Use the DEF Function name (): To define a function that is written as a indented block of the function body, returning the result as a return XX

For example:

def myabs (x):

If x >= 0:

return x

Else

Return–x

Variable parameters

Precede the parameter with an * number, the parameter received in the function is a tuple type, traversing

#可变参数

def mycalc (*nums):

Sum=0

For num in nums:

Sum+=num

return sum

Print (Mycalc ())

Iteration

Traversing a list or tuple through a for loop, which is called an iteration

Use for in to iterate over the List,for key in list: such as:

For item in MyList:

Print (item)

Use for in to iterate Dict,for k,v in D.items: such as:

user={"name": "Taoshihan", "Age": "100"}

For k,v in User.items ():

Print (k + "=" +v)

Slice

Take a list or tuple element, use the slice operator list[a:b], take the list of elements from A to B end (does not contain B)

Example: mylist=[1,2,3]

Print (Mylist[0:2]) output [1, 2]

function recursion

To find the factorial of n (n!)

def myfact (n):

If n==1:

Return 1

Return Myfact (n-1) *n

Print (Myfact (30))

Using tail recursion optimization to solve the stack overflow problem, the return statement cannot contain an expression, but the Python language does not introduce a tail recursion and therefore cannot be used

Solving the question of the Nottingham Tower:

def mymove (n,source,bridge,destination):

If n==1:

Print ("Move +" to "+destination" from "+source+")

Else

Mymove (N-1,source,destination, Bridge)

Print ("Move +" to "+destination" from "+source+")

Mymove (n-1,bridge,source,destination)

Mymove (5, "A", "B", "C")

Features of functional programming: Allows the function itself to be passed as a parameter to another function, and also allows the return of a function

[Python] Function basic