What does "for i in generator():" do?
This question already has an answer here:
for loop generates disposable variable if you use it like above. For example, a list object is used again and again in a loop but a disposable iterator is deleted automatically after use.
And yield is a term like return which is used in functions. It gives a result and use it again in loop. Your codes give you the number known as fibonacci.
def fib():
a, b = 0,1 #initially a=0 and b=1
while True: #infinite loop term.
yield b #generate b and use it again.
a,b = b, a + b #a and b are now own their new values.
for i in fib(): #generate i using fib() function. i equals to b also thanks to yield term.
print(i) #i think you known this
if i>100:
break #we have to stop loop because of yield.
Any function that contains a yield will return a generator. The for-loop runs that generator to return values one at a time.
When you run:
for i in fib():
print(i)
The actual mechanics of running the generator are:
_iterator = iter(fib())
while True:
try:
i = next(_iterator)
except StopIteration:
break
print(i)
As you can see, the i variable is assigned the result of calling next() on the generator to get the next value.
Hope that makes it clear where the i comes from :-)
for just ranges over the vaue of the expression. If the expression calls a function, then its value is whatever is returned from the function, so the for ranges over the result of that function.
Note that here though fib is not a function, it is a generator. It successively yields the value of each step.
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