Most tutorials start with installation, and write a simple program called "Hello World", I will follow this tradition just to make sure we cover the basics. Then I will move into control structures and some basic OOP, because almost everything we do in Python is OOPs.
Where to get python?
http://python.org/download/ and get whichever version you want, either 2.6.4 / 3.1.1 (at the time of this writing)
2.6.4 vs 3.1.1, which one?
It gets very technical when one is asked to explain the difference. Here is the shortest and simplest version:
Go with 2.X branch because 3.X branch has a lot of changes, and many existing books, codes and resources are written based on 2.X, so you are better off learning 2.X branch.
If you are very serious about learning Python, you will be happy with 2.X and then learn the differences later.
Write Hello World
Just like any other modern programming language,
Notice that, unlike C++, Python does not end with semicolon ;
Hack Python Program
As an beginner, you are better off hacking programs, rather than writing the entire program yourself. Once you understand what each line means, then you can write your own program. For example, just change the values or words around.
Unlike complex language like C++, Python is very simple, yet elegant. You do not always need to declare and define types and identifiers.
When we assign a number to any variable, Python knows it is an integer by default. When it is within double quote "", Python knows it is a string.
When you need floating point and other numerical types, then, yes, you do need to specify it. So use the option when it is mandatory.
Here is the major difference between the 3.X and 2.X. By default (2.X) if you do 3 divide 5, you get ZERO, whereas in 3.X you get an answer with demicals. If you are using 2.X, you must add one decimal point to any one of the numbers. For 3.X, you are no longer require to declare this extra decimal, because by default 3/5 will print a rounded answer.
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| IDLE 2.6.4
>>> 15/2
7
>>> 3/5
0
>>> 3.0 / 5
0.59999999999999998
>>>
>>> 3/5.00
0.59999999999999998
>>> |
Another way is to declare it a floating point, and round it up (check doc / google for answer).
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Filed under:Python Author:John Wong
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