# File: args2.py
# Program to demonstrate how functions handle variables
#
# Matt Bishop, ECS 36A, Winter 2019
#

#
# this one shows passing parameters
# it just prints the 3 arguments
def func1(a, b, c):
    print("Argument #1:", a)
    print("Argument #2:", b)
    print("Argument #3:", c)
    y = int(b)

#
# this one defines a local variable, x
# and assigns a value to it
def func2():
    x = 9
    print("func2: x =", x)
    
#
# this one changes the value of a parameter
def func3(y):
    print("func3: y =", y)
    y = 3456
    print("func3: y =", y)
    
#
# this one changes the value of a parameter
def func4(y):
    print("func4: y =", y[0])
    y[0] = 3456
    print("func4: y =", y[0])
    
#
# the main program
#
def main():
    # first, show how argumets are passed
    func1(7, "3", -3.14159)
    # now, show how local variables doesn't
    # affect variables in the caller
    x = 6
    print("main: x =", x)
    func2()
    print("main: x =", x)
    # show how changing parameters
    # doesn't affect variables in the caller
    y = 21
    print("main: y =", y)
    func3(y)
    print("main: y =", y)
    # finally, show how changing parameters
    # that are list elements does affect
    # variables in the caller
    y = [ 21 ]
    print("main: y =", y)
    func4(y)
    print("main: y =", y)
    
main()