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   ► KBTo/From GuidesASP ClassicLanguage Basics  Print This     

Cross Ref > Language Basics

By Mike Prestwood

ASP Classic versus PHP: A side by side comparison between ASP Classic and PHP.

 
Language Basics
 

Language basics is kind of a catch all for absolute beginner stuff. The items (common names) I chose for language basics is a bit random and include items like case sensitivity, commenting, declaring variables, etc.

Case Sensitivity

[Other Languages] 

Languages Focus

Case sensitiviy in this case is referring to commands and variable names. For example, are "printf" and "PrintF" equivalent? Are fullname and FullName equivalent? When you create commands, operations, methods, or variables should you worry about case?

ASP Classic:   No

ASP Classic is not case sensitive. My preference for all languages where case sensitivity does not matter is to use camel caps as in the first example above. Many developers coming from a case sensitive language prefer to use all lowercase.

Syntax Example:  

You can use any of the following:

Response.Write "Hello"
response.write "Hello"
RESPONSE.WRITE "Hello"
REsponse.WritE "Hello"
PHP:   Yes and No

PHP is case sensitive with variable names but not with commands. Although commands are case incenstive, I prefer to use all lowercase because it's easy to type and that's what I see most PHP coders doing and I see it on PHP.Net.

Syntax Example:

All of the following are equivalent:

echo "hello<br>";
ECHO "hello<br>";
Echo "hello<br>";
eCHo "hello<br>";

...but variables are case sensitive:

$fullname = "Mike Prestwood"; //These are two...
$FullName = "Wes Peterson";   //separate varialbes.




Code Blocks

[Other Languages] 

Languages Focus

The rules for code blocks within a language dictate where you can declare variables, how you "bracket" code, etc.

ASP Classic:   End Xxx

In .ASP html pages, you embed ASP code between <% and %>.

ASP Classic code blocks are surrounded by statement ending keywords that all use End such as End Sub, End If, and WEnd.

Syntax Example:
<%
Sub x
End Sub
 
If x Then
End If
 
While x
WEnd
%>
PHP:   { }

In .PHP html pages, you embed PHP code between <?PHP and ?>.

For PHP, JavaScript, Java,and C++, I prefer to put the first { at the end of the first line of the code block as in the example above because I see morePHP codeformatted that way (and on PHP.Net).

PHP Alternative Syntax

Although I don't like to use it, PHP offers an alternative syntax for if, while, for, foreach, and switch. These code blocks are surrounded by statement ending keywords that all use End with camel caps such as endif, endwhile, endfor, endforeach,and endswitch.

Syntax Example:
<?PHP
$x = "Yes";
//Simple if
If ($x == "Yes")
echo "hello world";
 
//If with a block of code.
If ($x == "Yes") {
echo "Hello world";
  echo "I am a PHP coder!";
}
?>




Comments

[Other Languages] 

Languages Focus

Commenting code generally has three purposes: to document your code, for psuedo coding prior to coding, and to embed compiler directives. Most languages support both a single line comment and a multiple line comment. Some languages also use comments to give instructions to the compiler or interpreter.

ASP Classic:   ' or REM

Commenting Code
ASP Classic, like all the VB-based languages, uses a single quote (') or the original class-style basic "REM" (most developers just use a quote). ASP Classic does NOT have a multiple line comment.

Preprocessor Directives - @ and #
An @ is used for preprocessor directives within ASP code (within <% %>) and a # is used for HTML-style preprocessor directives.

Note: ASP Classic does not support VB Classic's #If directive.

Syntax Example:
'Single line comment.
REM Old school single line comment.

 

Common Preprocessor Directives include:

<%@LANGUAGE=VBScript%>
<!-- #Include File="includes.inc" -->
PHP:   # or // or /* ... */

Commenting Code
Use the multi-line to comment out large blocks of code and to write multiple line comments.

Syntax Example:
#This is a comment in PHP.

//This is too!

/*
This is a multi-line
comment.
*/




Constants

[Other Languages] 

General Info: Computer Language Constants

A constant is just like a variable (it holds a value) but, unlike a variable, you cannot change the value of a constant.

ASP Classic:   Const kPI = 3.1459

Scope can be Public or Private. Public Const is the same as just specifying Const. As with variables, all constants are variants. You do not specify the type, it's implied.

Syntax Example:
Const kPI = 3.1459
Const kName = "Mike"
 
//Public variable:
Public Const kFeetToMeter=3.28, kMeterToFeet=.3
PHP:   define

In PHP, you declare constants using the define keyword:

define("CONST_NAME", "Value");

Constants in PHP are case sensitive. A common standard in PHP is to use all-uppercase letters, with underscores to separate words within the name.

Syntax Example:
define('FULL_NAME', 'Mike Prestwood');
define("AGE", 25);
  
echo "Your name is " . FULL_NAME . ".";
echo "You are " . AGE . ".";




End of Statement

[Other Languages] 

Languages Focus

In coding languages, common End of statement specifiers include a semicolon and return (others exist too). Also of concern when studying a language is can you put two statements on a single code line and can you break a single statement into two or more code lines.

ASP Classic:   Return

A return marks the end of a statement and you cannot combine statements on a single line of code. You can break a single statement into two or more code lines by using a space and underscore " _".

Syntax Example:
Response.Write("Hello1")
Response.Write("Hello2")
Response.Write("Hello3")

'The following commented code on a single line does not work...
' Response.Write("Hello4") Response.Write("Hello5")

'Two or more lines works too with a space+underscore:
Response.Write _
("Hello6")
PHP:   ;
Syntax Example:
echo "Hello";




Literals

[Other Languages] 

General Info: Programming Literals

A value directly written into the source code of a computer program (as opposed to an identifier like a variable or constant). Literals cannot be changed. Common types of literals include string literals, floating point literals, integer literals, and hexidemal literals. Literal strings are usually either quoted (") or use an apostrophe (') which is often referred to as a single quote. Sometimes quotes are inaccurately referred to as double quotes.

Languages Focus

In addition to understanding whether to use a quote or apostrophe for string literals, you also want to know how to specify and work with other types of literals including floating point literals. Some compilers allow leading and trailing decimals (.1 + .1), while some require a leading or trailing 0 as in (0.1 + 0.1). Also, because floating point literals are difficult for compilers to represent accurately, you need to understand how the compiler handles them and how to use rounding and trimming commands correctly for the nature of the project your are coding.

ASP Classic:   quote

String literals are quoted as in "Prestwood". If you need to embed a quote use two quotes in a row.

To specify a floating point literal between 1 and -1, you can preceed the decimal with a 0 or not (both work). In other words, preceding and following decimals are allowed (both .1 and 0.1). Trailing decimals are also allowed (1, 1., and 1.0 are all equivalent and allowed).

Syntax Example:
Response.Write "Hello"
Response.Write "Hello ""Mike""."
  
'Does ASP evaluate this simple
'floating point math correctly? No! 
If (.1 + .1 + .1) = .3 Then
 Response.Write "Correct"
Else
 Response.Write "Not correct"
End If
PHP:   quote or apostrophe

In PHP you can use quotes, or apostrophes as in "Prestwood", and 'Prestwood' for string literals. Use a slash in front of a quote or apostrophe to embed same type as in \' and \".

To specify a floating point literal between 1 and -1, you can preceed the decimal with a 0 or not (both work). In other words, preceding and following decimals are allowed (both .1 and 0.1). Trailing decimals are also allowed (1, 1., and 1.0 are all equivalent and allowed).

Syntax Example:
echo "Mike's drums are over there.<br>";
echo 'Mike said, "hi!"<br>';
  
//Does PHP evaluate this simple
//floating point math correctly? No! 
If ((.1 + .1 + .1) == .3) {
 Echo "Correct";
} Else {
 Echo "Not correct";
}




Variables

[Other Languages] 

Languages Focus

A variable holds a value that you can use and change throughout your code so long as the variable is within scope. With variable declaration, you not only want to know the syntax of how you declare a variable but you also want to know where. Are you allowed to declare a variable inline? What are the available scopes: local vs. global. Can you assign a value at the same time you declare a variable?

ASP Classic:   Dim x

ASP Classic is a loosely typed language. No variable types in ASP (all variables are variants). Declaring variables is even optional unless you use the Option Explicit statement to force explicit declaration of all variables with Dim in that script. Using Option Explicit is strongly recommended to avoid incorrectly typing an existing variable and to avoid any confusion about variable scope.

For example, at the top of my common include file, I have the following:

<%@LANGUAGE=VBScript%>
<%
Option Explicit
'...more code here.
%>
Syntax Example:
Dim Fullname
Dim Age
Dim Weight
 
FullName = "Mike Prestwood"
Age = 32
Weight = 154.4
 
'Declaritive assignment not supported:
''Dim Married = "Y"   '>>>Not supported.
PHP:   $x = 0;

PHP is a loosely typed language. No variable types in PHP. Declaring and using variables are a bit different than in other languages. In PHP, you identify and use a variable with a $ even within strings!

You assign by reference with & as in &$MyVar.

Syntax Example:
$fullname = 'Mike Prestwood';
$FullName = 'Wes Peterson'; //This is a different variable!
$Age = 38;
$Weight = 162.4;
 

echo "Your name is $fullname.
";
echo "You are $Age and weigh $Weight.
";




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