Syntax Comparison

Students

This is a comparison of the syntax of some popular programming languages, including Scala which we will be using on 5CS004. Where you see the word "TODO", please collaborate to fill in the blank parts of the tables. We will be adding to this page as the module progresses.

Useful language references

• PHP 5
• Scala
• Java 6
• Python 2.7

Basics

	PHP	Java	Scala	Python
Single line comment	// comment	// comment	// comment	# comment
Multi-line comment	/* comment */	/* comment */	/* comment */	Doesn't have multi-line comments.
Null object	NULL	null	null	None
Arithmetic operators	+,-,*,/,%,*	+,-,*,/,%,*	+,-,*,/,%,*	+,-,*,/,%,*
True and false	TRUE, FALSE	true, false	true, false	True, False
Boolean operators	&&, ||, !	&&, ||, !	&&, ||, !	and, or, not
Relational operators	<, >, <=, >=, ==, !=	<, >, <=, >=, ==, !=	<, >, <=, >=, ==, !=	<, >, <=, >=, ==, !=

Input / output

	PHP	Java	Scala	Python
Print to console	echo("hello");	System.out.println("Hello");	println("Hello")	print "Hello"
Read from keyboard	readline("")	BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); String kbd = in.readLine();	val kbd = readLine()	kbd = raw_input() # kbd is a string kbd = input() # kdb may be some other type

Selection

	PHP	Java	Scala	Python
if/else	if ($a==$b) { echo("same"); } else { echo("different"); }	if (a==b) { System.out.println("same"); } else { System.out.println("different"); }	if (a==b) println("same") else println("different")	if a==b: print 'same' else: print 'different'
else-if	if ($a<0) { echo("negative"); } elseif ($a==0) { echo("zero"); } else { echo("positive"); }	No equivalent.	No equivalent.	if a<0: print 'negative' elif a==0: print 'zero' else: print 'positive'
switch	switch ($i) { case 0: echo "i equals 0"; break; case 1: echo "i equals 1"; break; case 2: echo "i equals 2"; break; }	switch ($i) { case 0: System.out.println("i equals 0"); break; case 1: System.out.println("i equals 1"); break; case 2: System.out.println("i equals 2"); break; }	i match { case 0 => println("i equals 0") case 1 => println("i equals 1") case 2 => println("i equals 2") case _ => println("i is not 0, 1, or 2") }	No equivalent. Use "if" instead.

Iteration

	PHP	Java	Scala	Python
for	for ($i=0; $i<10; $i++) { echo($i); }	for(int i=0; i<10; i++) { System.out.println(i); }	for (i <- i to 10) println(i)	No equivalent
foreach	$a = array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10); foreach ($a as $v) { echo $v; }	for (int i : {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) System.out.println(i);	mylist.foreach((msg:String) => println(msg))	for i in range(10): print i
while	$i=0; while ($i<10) { echo $i; $i++; }	int i=0; while(i<10) { System.out.println(i); i++; }	var i=0; while(i<10) { println(i) i+=1 }	i=0 while i<10: print i i += 1

Functions

	PHP	Java	Scala	Python
Defining functions	function print_msg($msg) { echo $msg; }	No equivalent. Use methods.	def print_msg(msg: String) = { println(msg) }	def print_msg(msg): print msg

Compound types (arrays, lists, etc)

	PHP	Java	Scala	Python
Fixed length array	TODO	TODO	TODO	TODO
Mutable array	TODO	TODO	TODO	TODO
Associative arrays / hashes	TODO	TODO	TODO	TODO

Exception handling

	PHP	Java	Scala	Python
Raise an exception	throw new Exception("Division by zero");	throw new ClassNotFoundException();	throw new java.lang.ArithmeticException()	raise ValueError()
Handle / catch an exception	TODO	try { println(1/0); }catch( Exception e ) { System.out.println(""Can't divide by zero""); }	try { println(1/0) } catch { case exn : java.lang.ArithmeticException => println("Can't divide by zero") }	try: x = 1/0 except ZeroDivisionError as detail: print 'Handling run-time error:', detail

Dealing with types

	PHP	Java	Scala	Python
Convert object to different type	TODO	(float)1	1.asInstanceOf[Float]	(float)1

Classes, objects, methods, etc

	PHP	Java	Scala	Python
Root object	TODO	java.lang.Object	scala.AnyRef	object
Create an object	TODO	TODO	TODO	TODO
Call methods	TODO	TODO	TODO	TODO
Create and update instance attribute	TODO	TODO	TODO	TODO
Create and update class attribute	TODO	TODO	TODO	TODO
Create subclass	TODO	TODO	TODO	TODO