Recognition of the style of PHP4 marker

PHP4 style of marking

1.XML style

<?phpecho "This is an XML style tag";? >

2. Scripting style

<script language= "php" >echo "This is a script style tag";</script>

3. Short style

<?echo "This is a short style tag";? >

4.ASP style

<%echo "This is an ASP style tag";%>

Comments

Single line://

Multiple lines:/*............*/

Scalar data types

Boolean (Boolean): Only 2 values, True (True) and False (false)

String (String type): Sequential string sequence

Integer (Integer): contains only integers

Float (floating point type): Real number

$ is a scalar identifier, and all variables start with the $ sign

3 Ways to define strings

1. Single quotation mark (')

<?php$a= ' strings ';? >

2. Double quotation marks (")

<?php$a= "string";? >

3. Delimiter (<<<)

<?php$string=<<<str string str    //End qualifier must be another line?>

The difference between single and double quotes: single quotation marks are output by ordinary characters, and double quotes are the variables that are included replace them with actual values.

Escape character output extra "\"

Such as:

<?php$a= "string"; echo "\ $a"; echo "$a";? >

Output result: $a

Character connections (similar to Java (Java is +, here is.))

Such as:

<?php$a= "word"; echo "Hello". $a;? >

Output Result: Hello Word