Python Functions Swapping of numbers

Question

If we write a simple program in python as mentioned below, the variables get swapped

num1=5
num2=10
temp = num1
num1 = num2
num2 = temp

print(num1) //10

print(num2) //5

But if we perform the same thing inside a function, the values do not get swapped

def swap(x, y):
   
    temp = x
    x = y
    y = temp

Driver code

x = 2
y = 3
swap(x, y)
print(x)    //2
print(y)    //3

I want to know the concept that in first case it is getting swapped but in second case why it is not getting swapped ?

You've introduced local variables in the function that just happened to be named the same... If you had `def swap(a, b)`, what would you have expected? And when you set an equality, you're reassigning a reference, not "storing a value" to that variable name — OneCricketeer, Feb 01 '21 at 04:41

Mitchell Olislagers · Answer 1 · 2021-02-01T04:26:31.573

0

You can swap x and y like this

x,y=y,x

If you want to wrap it in a function

def swap(x,y):
    return y,x

x,y = swap(x,y)

edited Feb 01 '21 at 04:26

answered Feb 01 '21 at 04:25

That i know it can be swapped like this. I want to know the concept that in first case it is getting swapped but in second case why it is not getting swapped ? – Anil Feb 01 '21 at 04:26
Because your function is not returning anything. – Mitchell Olislagers Feb 01 '21 at 04:27
Returning doesn't matter. OP is expecting the passed in references to change – OneCricketeer Feb 01 '21 at 04:39

1 Answers1