一个php实现的简单语法高亮显示的函数，注意：这个函数设计的比较简单，可能对某些语法不能高亮显示，你可以自己扩充该函数的功能

function syntax_highlight($code){
  
    // this matches --> "foobar" <--
    $code = preg_replace(
        '/"(.*?)"/U',
        '&quot;<span style="color: #007F00">$1</span>&quot;', $code
    );
  
    // hightlight functions and other structures like --> function foobar() <---
    $code = preg_replace(
        '/(\s)\b(.*?)((\b|\s)\()/U',
        '$1<span style="color: #0000ff">$2</span>$3',
        $code
    );
  
    // Match comments (like /* */):
    $code = preg_replace(
        '/(\/\/)(.+)\s/',
        '<span style="color: #660066; background-color: #FFFCB1;"><i>$0</i></span>',
        $code
    );
  
    $code = preg_replace(
        '/(\/\*.*?\*\/)/s',
        '<span style="color: #660066; background-color: #FFFCB1;"><i>$0</i></span>',
        $code
    );
  
    // hightlight braces:
    $code = preg_replace('/(\(|\[|\{|\}|\]|\)|\->)/', '<strong>$1</strong>', $code);
  
    // hightlight variables $foobar
    $code = preg_replace(
        '/(\$[a-zA-Z0-9_]+)/', '<span style="color: #0000B3">$1</span>', $code
    );
  
    /* The \b in the pattern indicates a word boundary, so only the distinct
    ** word "web" is matched, and not a word partial like "webbing" or "cobweb"
    */
  
    // special words and functions
    $code = preg_replace(
        '/\b(print|echo|new|function)\b/',
        '<span style="color: #7F007F">$1</span>', $code
    );
  
    return $code;
}
  
  
/*example-start*/
  
/*
** Create some example PHP code:
*/
  
$example_php_code = '
// some code comment:
$example = "foobar";
  
print $_SERVER["REMOTE_ADDR"];
  
$array = array(1, 2, 3, 4, 5);
  
function example_function($str) {
    // reverse string
    echo strrev($obj);
}
  
print example_function("foo");
  
/*
** A multiple line comment
*/
  
print "Something: " . $example;';
  
  
// output the formatted code:
print '<pre>';
print syntax_highlight($example_php_code);
print '</pre>';
  
/*example-end*/