Do while loops have local variables in Python? -

i trying use while statement so:

    o = 0     while o == 0:         try:             n = int(raw_input("which number want begin with?"))             o = 1         except:             o = 0             print "please use valid number." 

however, when try use variable n later, gives me "local variable 'n' referenced before assignment' unboundlocalerror. means n cannot recognized variable in def using, because exists in while statement? possible? whole code:

import time sys import argv import os os.system("cls")  print "welcome number counter 2.0!" = true def program():     global     if == false:         os.system("cls")         o = 0         while o == 0:             try:                 n = int(raw_input("which number want begin with?"))                 o = 1             except:                 o = 0                 print "please use valid number." if n == "/historykeep false":     if == false:         print "command historykeep set false."     else:         = false         print "command set successfully." elif n == "/historykeep true":     if == true:         print "command historykeep set true."     else:         = true         print "command set successfully." if n == "/historykeep false":     n = raw_input("which number want begin with?")     elif n == "/historykeep true":     n = raw_input("which number want begin with?")      d = raw_input("how many seconds between each number?") d = int(d) total_s = n * d while n > 0:     print n     time.sleep(d)     n = n - 1 print "done in", total_s, "seconds in total!" end_q = raw_input("exit or retry? (e/r)") if end_q == "e":     os.system("cls")     print "exiting."     time.sleep(0.5)     os.system("cls")     print "exiting.."     time.sleep(0.5)     os.system("cls")     print "exiting..."     time.sleep(0.5)     os.system("cls")     exit(0) elif end_q == "r":     program()  program() 

you set a = true @ beginning. test if a == false , set n if is. test n == "/history.... n has not been set @ point.

you need make sure n assigned before use it. not enough mention in branch not taken.