header() redirect crashes apache

vt_dave

I have 2 quick questions and would appreciate any help that could be given.

First:
How taxing are string concatenations?
I had long querys

$q =  "update ".TBL_USER." SET ".
"field1='$updateObject->Field1, ".
"field2='$updateObject->Field2, ".
"field3='$updateObject->Field3, ".
"field4='$updateObject->Field4, ".
.......

for readability, but apache would crash on the query creation, i error_log($q) right after its creation and that never was output. I have since made my most used and larger queries just one GIGANTIC string.

Second:
I redirect users with

header("Location: http://".$_SERVER['HTTP_HOST']."/admin.php?mode=users&type=");

and when that happens apache crashes with the logs stating:

[error] Got list/counts sending to: http://localhost/admin.php?mode=users&type=
[info] master_main: Child processed exited prematurely. Restarting the child process.

This is becoming quite bothersom, and any help would be appreciated.

Thanks in advance
-Dave

zcketcher

Concatenations are not going to be a significant hit. However, you can speed things up if you drop the double quotes. When you echo/print anything in double quotes the engine is going to evalute the string looking for variables. If you you use single quotes it will just rip through it until it finds the ending single quote. Technically this is faster.

As far as your header statement: I may be wrong but SERVER HTTP vars can be a problem. If you going to do something like that I would use $SERVER['SERVER_NAME']. Using your example it would be:

...notice the single quotes and don't forget the exit statement right after the header statement.

header('Location: http://'.$_SERVER['SERVER_NAME'].'/admin.php?mode=users&type=');
exit;

..notice the single quotes and don't forget the exit statement at the end.

laserlight

How taxing are string concatenations?

Normally insignificant compared to expensive operations like file reads, database queries etc.
Actually, it doesnt make sense to use them the way you do.
You might as well use:

$q = "UPDATE " . TBL_USER . " SET
	field1='{$updateObject->Field1}',
	field2='{$updateObject->Field2}',
	field3='{$updateObject->Field3}',
	field4='{$updateObject->Field4}',
	...";

Also, if you are concerned about performance, it might be better to use arrays instead of objects to access result sets.
The reason why string concatenation is often used instead of variable interpolation (what we're doing in my example) is that there is a slight speed gain (less string parsing needed).

$q = "UPDATE " . TBL_USER . " SET"
	. "field1='" . $updateObject->Field1 . "',"
	. "field2='" . $updateObject->Field2 . "',"
	. "field3='" . $updateObject->Field3 . "',"
	. "field4='" . $updateObject->Field4 . "',"
	. "...";

But personally I prefer to use variable interpolation in the case of writing queries.

As far as your header statement: I may be wrong but SERVER HTTP vars can be a problem. If you going to do something like that I would use $SERVER['SERVER_NAME']. Using your example it would be:

I dont recognise vt_dave's error message, but I dont think $SERVER['SERVER_NAME'] improves on $SERVER['HTTP_HOST'], especially since the PHP Manual recommends the latter.
No harm trying, of course.