python - Local variable 'first' referenced before assignment -
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i local variable 'first' referenced before assignment error when run code.
def start(): global = [" "," "," "," "," "," "," "," "," "] global first first = randrange(2) def reverse(): if first == 1: first = 0 else: first = 1 if first == 1: turn = "x" else: turn = "o" that part of code error occurs. when paste code idle works no problem don't know why happening.
anyways, full code (unfinished tic tac toe):
from os import name os import system random import randrange time import sleep def cls(): system(['clear','cls'][name == 'nt']) def start(): global = [" "," "," "," "," "," "," "," "," "] global first first = randrange(2) def reverse(): if first == 1: first = 0 else: first = 1 if first == 1: turn = "x" else: turn = "o" while true: reverse() cls() printboard() print "" print "its %s's turn." % (turn) print "" move = raw_input("enter move (1-9): ") if move.isdigit() == true: move = int(move) if move in range(9): move = move - 1 if a[move] == " ": a[move] = turn else: print "incorrect move: place taken" reverse() sleep(2) else: print "incorrect move: number out of range" sleep(2) else: print "incorrect move: move not number" sleep(2) def printboard(): cls() print a[0],"|",a[1],"|",a[2] print "---------" print a[3],"|",a[4],"|",a[5] print "---------" print a[6],"|",a[7],"|",a[8] start()
python scans function body assignments, , if aren't explicitly declared global, creates local scope variable name. because assign first in reverse() function, , haven't explicitly declared first global within function's scope, python creates local variable named first hides global one.
it doesn't matter assignment comes after comparison; python implicitly declares local variables @ beginning of function.
to fix can declare first global within reverse() function, others have said, globals should avoided when possible.
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