comma in raw_input function

Question

What would be the output of this ? I see the output but not able to understand why that happens.

def multiple(x,y):  
    mul = x*y  
    return mul  

x=int(raw_input("Enter value 1 ")),  
y=int(raw_input("Enter value 2 "))  
print multiple(x,y)

Answer 1

In your code, the , at the end of the first raw_input means x is actually a tuple containing the user input. When you call the function, what you are actually doing is multiplying the tuple by an integer, which just multiplies the tuple ( x ) y times.

For example:

>>> x = 2,
>>> x * 5
(2, 2, 2, 2, 2)
>>> x = 2
>>> x * 5
10

Answer 2

The comma makes x equal to a tuple of size 1 (containing the int).

Simple test:

>>> a = 1,
>>> print a
(1,)

Answer 3

A large error with this is that if x and y are not numbers (aka a string), the function would be messed up. This can be fixed by saying: try: mul = float(x) * float(y) then, to catch the case when x or y are not numbers, except TypeError: print('Please do not give a string...') In this case, you want to show that mul is not valid, so you say, mul = None Now you can return mul in line with the try and except statements.

This ensures that the inputs are decimal point numbers, not characters.

Answer 4

First of all, you define a function called multiple and it multiplies x and y (parameters of multiple ), then returns that value. Then it takes input for two different variables, x and y (not the same as the parameters above), multiplies (by calling multiple ), and print s them out, which is what you see as output.

The comma however, simply defines x as a tuple.