De-reffing: $url = ${'url' . $site};  I.e. $url = $url3 if $site == 3;
	or: $s = 'url' . $site;  $url = ${$s};

function myprintvar ($name) { //echo ('<BR> <HR>');
        echo ($name . ':  ' . $GLOBALS[$name]); echo ("<BR>\n"); }

trim, clean, chop:  $str = trim($str);

// 2nd one is interesting and works; one above simpler.
function myprintvar ($name) { //echo ('<BR> <HR>');
	eval("global \${$name};");
        echo ($name . ':  ' . ${$name}); echo ("<BR>\n"); 
}


print_r($array);   The key debugging print. If printed to html, precede by <PRE>
function myprint_r ($a) { //echo ('<BR> <HR>');
	echo ('<PRE>'); print_r($a); echo ('</PRE> <P>'); }

<?php echo 'hallo world' ?> <P>


// conditional controlling plain HTML
<?php if ($a == 5): ?>
A is equal to 5
<?php else: ?>
Z is something else
<?php endif; ?>


$imin =  ($varoldrowlabels ? 0 : 1);  // alt. to if-then

// var. nmb of fn-args.   varargs / VARARGS in PHP
=>Can get the args as an array; or can name them but test for
	existence before using/reffing them.
function fn($a, $b, $c, $d, $e, $dopost) {
	$arr = func_get_args();
	foreach ($arr as $x) { echo('x: '. $x . "<BR>\n"); };
	if (! $dopost) { $dopost = 2; }; // default value
}

<H3> Include file "text"</H3>
<?php echo file_get_contents('text') ?>

// SHOW EVERYTHING of what php server has/knows
//foreach ($GLOBALS as $key => $val) { echo "$key => $val <BR>"; };
<?php phpinfo() ?>
//myprintvar('vardata1');
//myprintvar('php_errmsg');
//echo('GET  '); myprint_r($GLOBALS['_GET']);
//echo('POST  '); myprint_r($GLOBALS['_POST']);
//echo('POST2  '); myprint_r($_POST);
//echo('REQUEST  '); myprint_r($_REQUEST);
//foreach ($GLOBALS['_GET'] as $key => $val) { echo "$key => $val <BR>"; };
//foreach ($GLOBALS as $key => $val) { echo "$key => $val <BR>"; };


// PART 1: SETTING PARAMETERS, INCOMING VARS.
continue / break   (not: next, last)
For loop:
for ($i = strlen($findstr); $i >= 1; $i--) { };

function mytrim(&$val) {$val = trim($val);}; array_walk($menu2, 'mytrim');
$menu2 = array_map('trim', $menu2);
	map is simpler, but dups array.  walk does it in place.

//error_reporting(E_ALL);
echo "phpError: $php_errormsg\n";

Can use globals in functions AND set them there: like static vars.
global ${$varname};  $currentval = ${$varname};

FETCHING FILES
file_get_contents('text')  // file
file_get_contents('http://www.psy.gla.ac.uk/index.html')  // webpage
file_get_contents('http://www.psy.gla.ac.uk/index.html')  // remote webpage
   Must replace spaces in filenames by %20, at least for URLs:
$dfile2 = str_replace(' ', '%20', $dfile);
$buf = file_get_contents(mkurl($dfile2) .  '/');


SORTING
function cmp($a, $b) {
	$a = strrev($a); $b = strrev($b);
	return ($a == $b ? 0 : ($a > $b));
};
function testandprint($arr) {
	    //sort($arr);
	$arr = array_unique($arr);  // uniq !
	usort($arr, 'cmp');  /// sort by last domain, not first.
	....
}

STRINGS
$a == $b tests for eq of strings (diff. objects, but same string)
$arr[] = substr_replace($big , $bit, $pos, len);
	substr_replace replaces len (or 0) chars at pos
		by small or empty string inside big one.

$out = str_replace('TGT', $url, $orig);  no REs.  Always does global replace
$string[3] = 'a' replaces char 4 in a string.

pos, bit
strpos($haystack, $needle) -> pos of where substring first matches.
	(there are nocase versions,
strstr($haystack, $needle, $bool-before)
	finds where start of (1st instance of) needle is; splits haystack
	-> Returns half of haystack after/before that pt.  nocase version too.
substr_count($haystack, $needle) -> nmb. of non-overlapping instances of needle

ob_flush();  flush();
ob_flush();  flush();
ob_flush();  flush();
// however these still didn't progressively flush a big page


SED LIKE EDITS
Always use preg_match/replace, not ereg.
However with preg, the pattern must include delimiters e.g. // or ;;

s/abc/xyz/is  == preg_replace('/abc/is', 'xyz', $buf, 1);
s/abc/xyz/g  == preg_replace('/abc/', 'xyz', $buf); (global v.1)
$buf = preg_replace("|\n\s*#[^\n]*|s", "", $buf); (global v.2)
	Above does all by not eating next LF; unlike next:
        $buf = preg_replace("|\n\s*#.*?\n|s", "\n", $buf); BAD (global v.3)
	The diff is "match greedy while not LF" vs. "match min. to next LF"
	while ($count) $buf = preg_replace("|\n\s*#.*?\n|s", "\n",
		$buf, -1, $count); (global v.4)
        $buf = preg_replace("|\n\s*#.*?(?=\n)|s", "", $buf); (global v.5)
		Lookahead but don't eat the LF, though takes more chars than v.2
		See http://uk3.php.net/manual/en/regexp.reference.assertions.php

$obuf = preg_replace('|<TR><TD>|i', "\${0}$s3", $obuf, 1);
	Note \ to stop $0 being interpreted before RE; and {} in case s3 has a leading digit.
$c1 = preg_replace('/=(.*);/e',
			' \'=\' . base64_decode(${1}) . ";";',
			$c1);
	Note a) with /e replace string must be a valid line of PHP code.
		b) trouble with = as a string/char

<?php
$s2 = '123456789123';
$s2 = sprintf("%u", filesize('/var/mail/steve'));  $s = '';
while (strcmp($s2, $s)) {
	$s = $s2;
	$s2 = preg_replace('/(\d)(\d\d\d)(?!\d)/', '$1,$2', $s);
};
echo " Mail size:  $s\n<P>";
?>

// deletes incoming up to first <HR>.
//	Has to use non-greedy AND limit match to 1
echo preg_replace('/.*?<HR>/s', '<HR>',
	file_get_contents($urlroot . 'printchris2.php'), 1);

// deletes (URL) string after 3rd slash.
$targetbase = preg_replace('|^((.*?/){3}).*|s', '${1}', $target, 1);
a{5} = 'aaaaa';    abc{3} = 'abcabcabc';  \d{4,6} = any nmb. 4..6 digits long.
'((.*?str){3})' =
	all text from the start up to and including the 3rd occurrence of 'str'.
Replacing the 3rd occurrence probably needs something like:
	'((str.*?){2})str' and replacing $1 plus append the new text.

if (preg_match('/,del/', $f))  continue;   // deleted pmwiki pages
if (preg_match("|($pat)|", $buf, $matches)) {
	$link = $matches[1];  // I.e. must have $matches, and $1-> $m[1]

if (preg_match('/<\?php/is', $array[$k])) {
	while (preg_match('/<\?php.*</is', $array[$k])) {
		$array[$k] =
			preg_replace('/(<\?php.*)</s', '$1&lt;', $array[$k]);};
				// get rid of < within php
		$array[$k] = preg_replace('/(<\?php.*\n)/is', '<PRE>$1',
						$array[$k]);
			// Add PRE iff multi-line php
		$array[$k] = preg_replace('/<\?php/is', '&lt;?php', $array[$k]);
};


if (file_exists($dir . $f)) $stoparray[$f] = 1;
is_writable() 

//$a = array_merge($stoplist, $mustlist);
//foreach ($stoparray as $key => $val) { echo "$key => $val <BR>"; };
//foreach (array_keys($array) as $key) { echo "$key<BR>"; };
$array = array_keys($_REQUEST);   $who = $array[0];
	// gets request and uses only first key, no value.
	Don't know in fact what key you'll get back first if more than one.

//if ($f  &&  !preg_match("/.html$/", $f)) { $f = "$f.html"; };
//exec("ls $pattern", $plist); // echo, but split to 1 per line


}; };

SPLIT() split()
$parray = array();   exec("echo $pattern", $parray);
$pstr = implode('  ', $parray);  // all in a string of joined lines
$parray = preg_split('/\s+/', $pstr);   //$parray = explode(' ', $pstr);


//foreach ($stoparray as $key => $val) { echo "$key => $val <BR>"; };

<H3> UNIX callouts</H3>
system(' ./wtable  < calendar.tab  2>&1');  also works
// see DOCphp for more

$path_parts = pathinfo('/www/htdocs/index.html');
echo $path_parts['dirname'], "\n";  dir part
echo $path_parts['basename'], "\n";  filename, no dir, with extension
	== basename($file)
echo $path_parts['extension'], "\n";

Stuff on rel->abs URLs
You can usually use $_SERVER['HTTP_HOST'], $_SERVER['PHP_SELF'] and dirname()
to make an absolute URI from a relative one yourself: 
<?php
/* Redirect to a different page in the current directory that was requested
*/
$hostJ = $_SERVER['HTTP_HOST'];
$uriJJ = rtrim(dirname($_SERVER['PHP_SELF']), '/\\');
$extra = 'mypage.php';
header("Location: http://$host$uri/$extra");
exit;


//Date and file length:
<A name="TOP">Main text last changed </A>
<?php $x = pathinfo("$SCRIPT_FILENAME");  $x = $x['basename'];
	echo date('l j M Y.', filemtime("$x")) ?>
.............  Length:
<?php   $x = "$SCRIPT_FILENAME";  exec("wc $x", &$pstr);
$parray = preg_split('/\s+/', $pstr[0]);
$x = - (strlen($parray[2]) - 2);  // -1 instead for 1sigFig.
echo number_format(round($parray[2], $x)), " words\n";
$x = - (strlen($parray[3]) - 2);
echo "(", number_format(round($parray[3], $x)), " bytes) .\n";
?>


//Script date/time:
Last regenerated on <?php echo date('j F Y.') ?> // time right now

	// time this script was last modified.
Last explicitly updated on 
	<?php $x = pathinfo("$SCRIPT_FILENAME");  $x = $x['basename'];
		echo date('j M Y.', filemtime("$x")) ?>

Length:  Does 1,000 commas; does rounding to 2 sigFigs here.
<?php   $x = "$SCRIPT_FILENAME";  exec("wc $x", &$pstr);
        $parray = preg_split('/\s+/', $pstr[0]);
	$x = - (strlen($parray[2]) - 2);  // -1 instead for 1sigFig.
	echo number_format(round($parray[2], $x)), " words\n";
	$x = - (strlen($parray[3]) - 2);
	echo "(", number_format(round($parray[3], $x)), " bytes) .\n";
?> <BR>