{"id":95,"date":"2008-03-06T22:45:39","date_gmt":"2008-03-06T17:15:39","guid":{"rendered":"http:\/\/www.bin-co.com\/blog\/2008\/03\/learning-a-new-programming-language-the-hello-world-method\/"},"modified":"2008-03-06T22:45:39","modified_gmt":"2008-03-06T17:15:39","slug":"learning-a-new-programming-language-the-hello-world-method","status":"publish","type":"post","link":"https:\/\/www.bin-co.com\/blog\/2008\/03\/learning-a-new-programming-language-the-hello-world-method\/","title":{"rendered":"Learning a New Programming Language: The ‘Hello World’ Method"},"content":{"rendered":"

Hello World Learning<\/p>\n

Learning a new programming language is fun – and essential if you want to stay competitive. I try to learn new languages all the time(my latest target is Haskell). As a result, I have a system to make learning new languages easier. This is for people who already know a programming language and want to learn another one.<\/p>\n

Requirements<\/h2>\n

What you must have…<\/h3>\n
\n
The interpreter\/compiler of the language you are learning<\/dt>\n
You must be able to run the program after writing it.<\/dd>\n
Language reference manual\/documentation<\/dt>\n
Usually found at the site of the language. Put a shortcut to that on your desktop – because you will be using this all the time.<\/dd>\n
An easy to follow tutorial<\/dt>\n
Search for it in Google. If you find one and its hard to follow, ditch it and get another. You may not need this – as manual for most languages have a tutorial in them.<\/dd>\n
A ‘todo’ project that you cannot live without<\/dt>\n
This is what forces you to learn the language – more on this later.<\/dd>\n<\/dl>\n

What I would recommend you have…<\/h3>\n

Having this will help you learn – but its not necessary.<\/p>\n

\n
A Net Connection<\/dt>\n
You may want to ask your doubt on the IRC channel. Or on a forum. Or to google the error message you got.<\/dd>\n
A Decent IDE<\/dt>\n
This may make your job easier – but if you have notepad, that’s enough.<\/dd>\n<\/dl>\n

What you don’t need<\/h3>\n
\n
Books on the language<\/dt>\n
You may need a book to master the language – but you don’t need one to learn it.<\/dd>\n
A Teacher<\/dt>\n
Its helpful to have someone to clarify the doubts you may have – but no one can teach you anything you cannot learn yourself<\/strong>.<\/dd>\n<\/dl>\n

The Hello World Script<\/h2>\n

First you have to create the ‘hello world’ application. This is more than just ‘print “Hello World”‘ – it will act as a cheatsheet for you until you familiarize yourself with the language<\/strong>. The point of this application is to use all the most commonly used elements of a language and putting it in a single place<\/strong> so that you can refer to it later.<\/p>\n

Your first job is to go to the tutorial, the manual and the internet until you create the Hello World application with the following stuff in it. I will provide an example – how the ‘hello world’ application will look in PHP.<\/p>\n

After each step run the application and make sure it works.<\/p>\n

\n
Print “Hello World\\n”<\/dt>\n
\n

Why do you think we call it a hello world application? Write the code to print a string ‘hello world’ and save it<\/strong> to a file. Now run it using the interpreter<\/strong> – and make sure it works – see it in action.<\/p>\n

\n\/\/ Printing(IO)\nprint \"Hello World!\\n\";\n\t<\/code><\/pre>\n<\/dd>\n
Comments<\/dt>\n
\n
Put a single line comment(like \/\/) on top of the “print ‘hello world'” code and if your language supports it, a multiline comment(\/* – *\/) as well. Run the script to make sure the comments work as advertised.<\/p>\n
\n\/\/ Single line comment.\n\/*\nMulitline comment.\n*\/\n\t<\/code><\/pre>\n
I was just kidding about running the script to test the comments – you did’nt do it, did you?<\/p>\n<\/dd>\n
Use a variable(a string and an integer) and a concatenation operator.<\/dt>\n
\n
Create a variable called name(string) – and give it your name as the value. Create another integer variable and give it the current year. You don’t have to find it programatically – just put it as 2008 or something. Now you have to print out the a string “Hello, <name> – Welcome to year <$year>”. This string will let you concatenate two different type variable to a string – and it makes me feel like a time traveler ;-).<\/p>\n
Yeah – the value of variable name should appear at <name>. Use the concatenation operator if possible – in PHP, write<\/p>\n
print \"Hello, \" . $name . \" - welcome to year \" . $year;<\/code><\/pre>\n
instead of <\/p>\n
print \"Hello, $name - welcome to year $year\";<\/code><\/pre>\n
This is because different languages have different concatenation operators. The other stuff is the same almost universally. + refers to addition. – refers to subtraction. * is multiplication. My point is that if you know the operators for one language, you know the operators for almost all languages<\/strong>. But the concatenation operator differs from language to language – its ‘+’ in javascript, ruby. Its ‘.’ in Perl, PHP, etc.<\/p>\n
There are exceptions to this rule – ‘=’ is the equality operator in SQL while it all other language its ‘==’. The assignment operator is ‘:=’ in pascal – in all other it is ‘=’. If you notice any difference in any operator write some code using that operator in this section.<\/p>\n<\/dd>\n
Use if\/else if\/else<\/dt>\n
\n
Create something like this pseudo code…<\/p>\n
if (year > 2008) {\n\tprint \"Welcome to the future - yes we have flying cars!\"\n}\nelse if(year < 2008) {\n\tprint \"The past - please don't change anything. Don't step on any butterflies. And for the sake of all that's good and holy, stay away from your parents!\"\n}\nelse {\n\tprint \"Anything wrong with your time machine? You have not gone anywhere, kiddo.\"\n}<\/code><\/pre>\n
In PHP, this section will look like this…<\/p>\n
\/\/If,else conditions\nif ($year > 2008) {\n\tprint \"Welcome to the future - yes, we have flying cars!\";\n}\nelse if($year < 2008) {\n\tprint \"The past - please don't change anything. Don't step on any butterflies. And for the sake of all that's good and decent, stay away from your parents!\";\n}\nelse {\n\tprint \"Anything wrong with your time machine? You have not gone anywhere, kiddo.\";\n}\nprint \"\\n\";\n\t<\/code><\/pre>\n
If you use switch(and the new language supports switch), you can write an example of switch here. <\/p>\n<\/dd>\n
Print ‘Hi there!’ 3 times using a for loop<\/dt>\n
\n
A PHP example of using for loop(my all time favorite loop)…<\/p>\n
\/\/ For loop\nfor($i=0; $i<3; $i++) {\n\tprint \"$i) Hi there!\\n\";\n}\n\t<\/code><\/pre>\n<\/dd>\n
Create a list(array) and iterate through it using while\/for\/foreach loop.<\/dt>\n
\n
I am using a while loop here – to keep things different…<\/p>\n
\n\/\/Numerical Array, While\n$rules = array(\n\t'Do no harm',\n\t'Obey',\n\t'Continue Living'\n);\n$i = 0;\nwhile($i<count($rules)) {\n\tprint \"Rule \" . ($i+1) . \" : \" . $rules[$i] . \"\\n\";\n\t$i++;\n}\t<\/code><\/pre>\n<\/dd>\n
Create a hash(associative array) and iterate through it.<\/dt>\n
\n
If the language you are going to learn have ‘foreach’, this maybe the best time to use it…<\/p>\n
\/\/ Associated array, foreach\n$associated = array(\n\t'hello'\t=>\t'world',\n\t'foo'\t=>\t'bar',\n\t'lorem'\t=>\t'ipsum'\n);\nforeach($associated as $key => $value) {\n\tprint \"$key: $value\\n\";\n}<\/code><\/pre>\n<\/dd>\n
Create a function with an argument and a return.<\/dt>\n
\n
If you need, you can create an example for call by reference, optional arguments, default argument value, variable argument count etc. as well – but they are not essential. Make sure you include the code to call a function as well.<\/p>\n
\/\/ Function, argument, return, call\nfunction hello($name) {\n\treturn \"Hello \" . $name;\n}\n$hello_string = hello(\"Binny\");<\/code><\/pre>\n<\/dd>\n<\/dl>\n
Optional Code<\/h3>\n
I don’t usually included some of these in my ‘hello world’ scripts – but they can be useful in some cases. Some may find them useful – so if you think you are going to use any of these, include it in your file.<\/p>\n
\n
Class, Objects, Member variables and functions<\/dt>\n
\n
If you are a big fan of OOP, create the code for a class. Make sure it has all the following elements…<\/p>\n