What is the point of the elif statment?

[Cash Fulton]

What's the point of the elif statement? Why not just keep the if and else statements and leave it at that? Can't the if statement be replaced with just if? Thanks.

 

[Mark44]

What's the point of the elif statement? Why not just keep the if and else statements and leave it at that? Can't the if statement be replaced with just if? Thanks.

It's short for else if. A simple if ... else statement is used to choose one of two possible alternatives. If you have to choose among three or more alternatives you want a control structure that looks like this (using C rather than python, though):

if (val == opt1)
{
   // Option for opt1
}
else if (val == opt2)
{
   // Option for opt2
}
else
{
   // Otherwise do this
}

If my code has to choose among more possibilities, I can add more else if clauses (or elif in python).

 

[D H]

Compiled languages tend not to have an elif statement, or something similar. They instead use something along the lines of

if (condition) {
    do_this;
} else if (other_condition) {
    do that;

The elif statement, or something similar, is much more common in scripting languages. With python, it's almost essential because of the indentation rules and PEP8, the python indentation standard. Consider the following:

class Foo :
    def fun (self, val) :
        if val == 0 :
            self.handle_zero ()
        else :
            if val == 1 :
                self.handle_one ()
            else :
                if val == 2 :
                    self.handle_two ()
                else :
                    # Lines are supposed to be at most 79 characters long in python.
                    # Do you see how quickly I'm running out of space?
                    # There are lots of enums with 16 or more members.
                    pass

Many other languages have a switch statement. Python doesn't. You either need to use a dictionary, an incredibly ugly stair-stepped if ... else if ... else if ... sequence of tatements, or you could use elif.

 

[Integrand]

See 4.1 in https://docs.python.org/3/tutorial/controlflow.html for justification.

Can't the if statement be replaced with just if?

This doesn't make sense. I'm guessing you mean "Can't the elif statement be replaced with just if?" If so, the following are not logically equivalent:

if A:
  a()
elif B:
  b()
else:
  c()

if A:
  a()
if B:
  b()
else:
  c()

In the latter block, the first test is independent of the second.