Python crash course part 5 (control flow)

Until the last post, I guess I've kind of skipped over some very basic thing: control flow.

So here is a script with simple class, defining some lists as its fields, a method for checking if a string is in one of this lists (using if - elif - else), then for in ("foreach") and for .. in range(...) ("classic for") as well as a while loop example.

Listing 1

# !/usr/bin/python3

class Fellowship:

    # method declaration, self - instance (the method is called      # with only 1 arg) in parentheses

    def check(self, name):

        # these are instance fields:

        self.hobbits = ["Frodo", "Bilbo", "Sam", "Merry", "Pippin"]

        self.people = ["Aragorn", "Boromir"]

        self.dwarves = ["Gimli"]

        self.elves = ["Legolas"]

        self.istari = ["Gandalf", "Saruman", "Radagast"]

        # if, elif, else

        if name in self.hobbits:

            print(name + " is a hobbit")

        elif name in self.istari:

            print(name + " is a wizard")

        elif name in self.people:

            print(name + " is a human")

        else:

            print(name + "? - I don't know what he is")

def main():

    # object creation

    fellowship = Fellowship()

    # calling a method

    fellowship.check("Gandalf")

    print("HOBBITS:")

    # for ("foreach") loop

    for name in fellowship.hobbits:

        print(name)

    

    print("ISTARI:")

    # for ("classic", with number)

    for i in range(0, len(fellowship.istari)): # 0..len(...)-1

        print(fellowship.istari[i])

    # while loop

    

    number = 0

    print("PEOPLE:")

    while(number<len(fellowship.people)):

        print(fellowship.people[number])

        number = number+1

if __name__ == "__main__":

    main()

The result of calling this code is as follows:

Gandalf is a wizard

HOBBITS:

Frodo

Bilbo

Sam

Merry

Pippin

ISTARI:

Gandalf

Saruman

Radagast

PEOPLE:

Aragorn

First, the call to check() method, then for in loop to enumerate the hobbits, then for .. in range(...) one to list the Istari, and last but not least: classic while to list people.