improving Performance

Anon

Hello all

Some of my scripts really take long time to execute and I am concerned about its perfomance. I am using a lot of loops. While loop and inside the while loop, there are for loops. Could someone give me some tips to improve the performance, telling what kind of coding style could slow the script and what kind of coding style could make it faster.

Thanks for reading this

Anon

Not about loops at all. You did not write if you're using databases and what kind of them. But if you do - don't forget about indexing! About correct indexing. It've happened to me that my database parts worked slowly even with indexes. And then I rebuilt them correctly - now it works fine and really fast.
Sure, you know this - but it is just a tip :-)
As for loops - I always try not to use statements like this:
while (){
if (length(trim($x.$y))<=10){
//code
}
}
It is much faster to do:
$xy_length=length(trim($x.$y);
while (){
if ($xy_length<=10){
//code
}
}
In this case this length is calculated only once instead of being calculated in each loop. It is especially critical with loops.
Again, sure you know this already :-)

Anon

Yes I am using MySQL database and tables are indexed. Still very slow. I am using comparing sometimes Dates and I am also using:
if(strLeng($link)<8){
blah blah..
}
in while loop which is inside of another while and I am always making query to database in each while and for loop. Do you think making queries inside nested while loops slows the whole thing? and if that is the case, I would not know how to solve. These SQL queries cannot be skipped. You know what I mean.

Do you have good timer code so that I will check which of the loops is taking more time?

By the way, I must use this style:
while (){
if (length(trim($x.$y))<=10){
//code
}

Because My while loop is like:
while($row = mysql_fetch_array($query)){
$link = $row["links"];
}

so the link itself is in database. I would appreciate any performance improvement suggestions.

Thanks annchen.