Difference between return and yield

return： Used in functions to return a value , After returning this value, the program will not continue to execute , A function returns a value directly and ends

>>> def lll():
...   return 10
...   print(' I am a little monster ')
...
>>> g=lll()
>>> print(g)
10

yield： Generate a number , But it doesn't return directly , Instead, generate a generator

As shown in the following code , We can think of the code running to yield Get a generator object at g, Stop here , We have to call next Method to keep the code running , While using next After method , Continued to run... In the function yield Statement returns a value or variable , Next time I meet yield And stop again , This is a bit like an iteration , We must rely on next Go to the next step

In the following code , When using yield 6 to r When you assign , We can see the variables in the output r It shows a null value , in other words yield 6 Returned when , No assignment to variable r, So we use next Method to run the output statement r It's a null value , So we need to use send Method , Pass a value to the function to be run print('s:',s) sentence , So the output gets s Right behind send Value delivered 10

>>> def ret():
...   r=yield 6
...   print('r:',r)
...   print(' This output statement is to let you clearly understand next Where to stop after running ')
...   s=yield 8
...   print('s:',s)
...
>>> g=ret()
>>> print(g)
<generator object ret at 0x000001A4C1BCB890>
>>> print(next(g))
6
>>> print(next(g))
r: None
 This output statement is to let you clearly understand next Where to stop after running 
8
>>> print(g.send(10))
s: 10
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
StopIteration