#python program to swap two numbers without using temp variable (addition-subtraction operation)

#getting input from user and storing in num1 and num2 variables

num1=input("Enter value for num1: ")

num2=input("Enter value for num2: ")

#validating user input

try:

    num1=int(num1)

    num2=int(num2)

    print("you have entered valid numbers")    

    

    #add both numbers and store in num1 variable

    num1 = num1 + num2

    #subtract num2 from num1 and store result in num2 to swap the value in num2 variable

    num2 = num1 - num2

    #now num2 have num1 value, subtract num2 again from num1 and store result in num1 to swap the value in num1 variable

    num1 = num1 - num2

    #print result

    print("num1 value is %d"%(num1))

    print("num2 value is %d"%(num2))

    

        

except:

    print("you have entered an invalid number")

 

Enter value for num1: 15

Enter value for num2: 18

you have entered valid numbers

num1 value is 18

num2 value is 15

 

Enter value for num1: x

Enter value for num2: y

you have entered an invalid number