Return True Stop The Loop In Python?

I am still a beginner but does not know why the 'return True' in a 'for loop' stop the loop after the first pass. If I use something else than 'return', everything is fine. def roc

Solution 1:

return statement is to return a value from a function. So, if you use return the control will be transferred to the calling function.

If you want to break out of the loop, you need to use break statement.

For example,

def tempFunc1():
    i = 1return i
    print "leaving tempFunc1"print tempFunc1()

It prints just 1. It doesnt print leaving tempFunc1 because, the function has returned to the caller before executing the print "leaving tempFunc1" statement.

Solution 2:

If you want to return True, but still keep looping, you may need a pattern like this. I'm calling the variable retval but you can call it anything that makes sense

defroc_valid(self,cote_x,cote_y):
    from graph_chess import board
    p = board()
    side=(side_x,side_y)
    retval = Falseif side == (0,0):
        for (x,y) in (0,1),(0,2),(0,3):
            print(King.ok_to_move(self,x,y))
            if p.getPiece(x,y)==""and king.ok_to_move(self,x,y):
                retval = Truereturn retval

Solution 3:

You can use the yield statement. A return statement stops the function and immediately and returns the value while yield statement will return the value and but continues where it left.

if side == (0,0):
    for (x,y) in (0,1),(0,2),(0,3):
        print(King.ok_to_move(self,x,y))
        if p.getPiece(x,y)==""and king.ok_to_move(self,x,y):
            yieldTrue

Now use: list(roc_valid(self,cote_x,cote_y)) to get a list of all returned values or just next(roc_valid(self,cote_x,cote_y)) to get only the first value.

Demo:

deffunc():
    for i in xrange(5):
        if i % 2: 
            yieldTrue... >>> list(func())          #all returned values
[True, True]
>>> next(func())          #Just the first returned valueTrue

Related: The Python yield keyword explained