使用* args变量在函数中传递多个变量

Question

I'm new to python. Look at this script please:

def myfunc(*args):  
    print len(args)
    if args == 3:
        for arg in args:
            print arg
    else:
        print "exit"
a, b, c = 1, 2, 3
myfunc(a, b, c)

As you can see, the number of arguments passing to function is three. Now condition args==3 is True but the else portion is executed. While on other hand if if condition is false then that portion of code is executed and else is skipped.

Can you explain why the if statement is executed on False condition ?

Answer 1

No, args == 3 is not True . You probably meant len(args) == 3 .

Answer 2

I think you must be doing len(args)==3 instead of args==3 :

if len(args)==3:

the condition args==3 is never going to be true as args becomes a tuple inside the function.

so even if you pass myfunc(3) , then also you'll be matching (3,)==3 , which is False .

Answer 3

You have to apply len(args) == 3 instead of args == 3 because if you use args then it is a list of tupple and if you check against it must go to else condition.

def myfunc(*args):

    if len(args) == 3:
        for arg in args:
            print arg
    else:
        print "exit"
a, b, c = 1, 2, 3
myfunc(a, b, c)

This code give you an expected result.