python global variable not defined in for loop

Question

This code gives the error: UnboundLocalError: local variable \'LINES\' referenced before assignment but LINES is clearly initialized since if I com

Answer 1

As Desired Login said,

Since you assign to LINES in your example function, python knows not to use the global variable, but you attempt to access this variable before you define it.

This is not the end, you can fix this by using a global keyword, telling python that the LINES in the function is the same as the LINES outside of the function.

Try:

LINES = []

def foo():
  global lines
  for prob in range(1,3):
    print "len(lines) = %d" % len(LINES)
    LINES = []

if __name__ == "__main__":
  foo()