Hello everyone.

I am new to functions, and don't uderstand entirely how they work.

I have this repeated in my code many times

$categorya = ucwords(str_replace("_", " ", $category));

How do i make a function that does that (and therefore take it out of my codes)?

Would it be advised?

Think of functions as a repeatable action which can be taken and a result returned. A function here is totally appropriate because you can encapsulate your functionality. Here is the definition of your function (you can rename it whatever you want).

PHP Code:

function cleanWords( $category )
{
    return  ucwords(str_replace("_", " ", $category));
} 


Then in your code, you simply call the function:

PHP Code:

$category = cleanWords( $category ); 


The value returned by the function is assigned to $category. You already know how to use functions: str_replace() is a function whose result is submitted to the function ucwords() and assigned to a variable.

Well explained. THat made sense to me without needing to read it twice.

I heard somewhere that a functions are slow. Any opinions with regards to that.

I do not think so.

Functions are used to clean up and make code even faster.

If you had to repeat say:

ucwords(str_replace("_", " ", $category));

30 times becuase you had to check 30 variables it would take up alot more time and effort then if you used a function to return a TRUE or FALSE value.

Cool. Thanks for your input.

The basic rule of thumb is, if you need to use the same code more then once within your script, then it belongs in a function. PHP going over the function once is faster then it going over, say, 400 lines twice.

Does php do some degree of compilation then or is it an entirely interpreted language? If the latter, then all a function call does is jump to another place in your code and continue executing. It would be no faster or slower than writing it all inline, maybe with a couple of instructions worth of overhead to jump and store the return address.

You wouldn't get that far without functions let's face it!

0beron, you are right in that PHP is strictly interpretive and that the overhead of calling a function is minimal. So in comparison to a compiled module, the increased efficiency of function utilization is minimal. However, from a development, cognitive and maintenance standpoint, the value of functions and PHP objects are inestimable in that it provides developers the basis for constructing our own application frameworks.

You are right. Though Zend Optimiser and similar addons (such as Turck) reduce speed by "compiling" PHP, the overhead of functions is still small in some cases.

I just did an experiment to see how much overhead. I wrote two small functions and called them three times within a loop that executed them 100,000 times, then took the code from the functions and pasted it three times within another loop which also executed 100,000 times. When I outputted data (I was working with strings), the function calls were much faster by a factor of 6 seconds. When I enabled output buffering, the function calls were slower by about 0.8 seconds.