len
S = ' jingdong appliance Section '
DEF my_len (): # custom function
I = 0
for K in S:
I + =. 1
Print (I)
my_len () # function call
Function
defines the future, you can call at any place that needs it
does not return the length, simply print
Returns the importance
A, B
len (A) # built-in function
len (B)
DEF my_len (): # custom function
I = 0
for K in S:
I + =. 1
Print (I)
return I # Return Value
length = my_len ()
Print (length)
len ()
. 1, can not be changed, only calculate the length of the string
2, but the result is output
three cases # return value
returns no value - returns None
not write return
DEF FUNC ():
L = [ ' gold boss ' , ' brother ' ]
for I in L:
Print (I)
Write only return: the end of a function to continue
DEF FUNC ():
L = [ ' gold boss ' , ' brother ' ]
for I in L:
Print (I)
return
Print ( " brother brother brother ' )
red = func()
print(ret)
return None - not commonly used
DEF FUNC ():
L = [ ' gold boss ' , ' brother ' ]
for I in L:
Print (I)
IF I == ' gold boss ' :
return
Print ( ' = ' * 10)
It returns a value that
can return any data type
def func():
return [1,2,3]
print(func)
red = func()
print(ret)
As long as the returns can be received
if more than one person return, only the implementation of a program in the first
return multiple values
receiving a number of variables: how much of the return value variable with the number of accepted
def func2():
return 1,2,
r1,r2, = frunc2()
print(r1,r2)
Receiving a variable: a neuron progenitor is obtained
def func2():
return 1,2,3
r = func2()
print(r)
What is the parameter
syntax parameters of said
parameter concepts and arguments
DEF my_len (S): # custom function parameters only 0. Accept parameters, in the form of parameters, parameters,
I = 0
for K in S:
I + =. 1
return I
S = ' jingdong appliance Section '
RET = my_len (S) # pass parameters: transmission parameters, the actual parameters, arguments
ret = my_len ([1,2,3,4 ,])
Print (RET)
parameter
No parameters
when defining the function and calling the function in brackets do not write the contents of
a parameter
of what passed is what
multiple parameters
positional parameters
def my_sum(a,b):
res = a+b
return res
ret = my_sum(1,2)
print(ret)
Standing on the angle argument:
a reference position in accordance with the transmission
in accordance with the key parameter passing
mix can be: However, according to the need to pass a reference position, then the parameter passing by keyword
can not pass a plurality of values to the same variable
DEF my_sum (A, B) :
Print (A, B)
RES = A + B
return RES
RET = my_sum (. 1, B = 2 )
Print (RET)
Standing on the parameter of the angular
position parameters: must pass, and there are several parameters to pass several values
default parameters: can not pass, if the default parameter is not passed, if used to pass pass
DEF Classmate (name, Sex = ' M ' ):
Print ( ' % S:% S ' % (name, Sex))
Classmate ( ' brother ' )
Classmate ( ' small dream ' )
Classmate ( " dream " )
Classmate ( ' Franco ' , ' female ' )
Only when the function is called
According to the position Biography: write directly to the value of the parameter
by keyword biography: keyword = value
Defined function of time
Location parameters: Direct-defined parameters
default parameters: Keyword: Parameter name = 'default values'
dynamic parameters: You can accept any number of parameters
plus before the parameter name * , accustomed to the parameter name args,
before the parameter name plus ** , habit parameters name kwargs
order: location parameter, * args, default parameters, ** kwargs
def sum(*args):
n = 0
for i in args:
n+=i
return n
print(sum(1,2))
print(sum(1,2,3))
print(sum(1,2,3,4))
def func(**kwargs):
print(kwargs)
func(a = 1,b = 2,c = 3,d = 4)
func(a = 1,b = 2,c = 3,)
func(a = 1,b = 2,)
There are two dynamic parameters:
Can take any arguments
* args: accepted in accordance with the value of the position parameter passing, organized into a neuron progenitor
** kwargs: accepted by keyword parameter passing values, organized into a dictionary
args must precede kwargs
DEF FUNC (* args, ** kwargs):
Print (args, kwargs)
FUNC ( 1,2,3,4, A = ' AAAAA ' , B = ' SSSSSS ' )
Another parameter passing parameters dynamically
DEF FUNC (* args): # standing on the angle parameter, coupled to the variable *, is a combination of all the values coming.
Print (args)
FUNC ( 1,2,3,4,5 )
L = [1,2,3,4,5 ]
FUNC ( * L) # standing on the angle of the argument: * to add a sequence, this sequence is broken up in order
DEF FUNC (** kwargs):
Print (kwargs)
FUNC (A =. 1, B = 2 )
D = { ' A ' :. 1, ' B ' : 2 }
FUNC ( ** D )
Notes functions
DEF FUNC ():
'' '
This function implements what function
Parameter 1
Parameter 2
: return: the length of a string or list
# ' ''
Pass
function
1. The function definition DEF
2 . Calling function
3. The function returns the value of the return
argument 4 function
parameter:
positional parameters: must pass
* args: can take any position of a plurality of parameters
default parameters; can not pass
** kwargs: keyword parameters can accept multiple
arguments: mass participation by location, by keyword parameter passing