Coffee on the Keyboard

System.out.println(”Hello World!”)

So I’ve been getting used to a couple new languages lately, mostly Ruby and Java but also Python and C++ for comparison. Coming from PHP, VBScript and JavaScript has confused the hell out of me.

The hardest part so far is not strict types, which I expected would mess me up. It’s block-level scope. For example, in PHP you could:

<?php
if ( $_GET['name'] ) {
    $name = $_GET['name'];
} else {
    $name = "World";
}
echo "Hello $name!";
?>

But in C++ and Java, variables defined within any block (section wrapped in {}), are only visible in that block and its descendant blocks, so when I tried

class HelloWorld
{
    public static void main ( String[] args )
    {
        if ( args.length > 0 ) {
            String name = args[0];
        } else {
            String name = "World";
        }
        System.out.println("Hello "+name+"!");
    }
}

it wouldn’t compile, saying “name cannot be resolved.” It took me a while to figure this one out.

Fortunately I had some help from a friend but honestly it still seems counter-intuitive to need to declare a value before copying a fixed value. For the record, here’s a version of the last class that works:

class HelloWorld
{
    public static void main ( String[] args )
    {
        String name;
        if ( args.length > 0 ) {
            name = args[0];
        } else {
            name = "World";
        }
        System.out.println("Hello "+name+"!");
    }
}

Tags: block level, java, programming, scope, syntax

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This entry was posted on Friday, May 2nd, 2008 at 5:58 pm and is filed under Articles, Code. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

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