Is php compiled?

I'm with you arc!

All programming languages are script based. You use predefined verbs, nouns and other such constructors to create an instruction to the script parser to create machine executable code.

The difference between say C and PHP is that the C code is parsed before execution, whereas PHP is parsed during execution.

The C compiler and the PHP parser do exactly the same thing - that is they read the script and use blocks of predefined instructions (defined by the parser author) that perform the function described in the script.

If you want to called a pre-parsed script compiled and an 'on-the-fly' script interpreted fine, but this distinction does not change the fact that they are both "interpreted" at some point.

And yes, I have been involved in writing compilers.

That still strongly differs from any definition of interpretation and compilation I've ever heard Slaine.

Then post the definitions you have heard and we can look at the validity of them.

compilation/compile/compiled are meaningless word. Interpretation is the only thing that means something.

Also don't forget that not so long ago BASIC was parsed on-the-fly but now it is pre-parsed. That alone should show that the distinction is hazy.

Compilation: the process of creating binary code from source code.

Interpretation: the process of acting on the instructions of code in some form to produce immediate results.

So all languages get interpreted in some way (by the CPU, if not by anything else).
But only when a translation is done can you call it compiled.
PHP is never translated to some other form of code, the pre-existing machine code snippets are directly called, not pieced together to form compiled code.

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compile

v 1: get together [syn: collect, accumulate, pile up, amass, hoard] 2: put together out of existing material; "compile a list" [syn: compose] 3: use a computer program to translate source code written in a particular programming language into computer-readable machine code that can be executed

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The third definition is quite vague (what is computer-readable?), so I'll ignore it. But the second definition exactly matches what I mean. Compilation means that pieces of machine code are put together to form code. In interpretation, the pieces are not put together, they are called in succession, but always will the interpreter itself be there in-between.

For the time being let us ignore any optimistation that may take place during any kind of interpretation/compilation. I am also not denying that pre-processed code is different to code processed on the fly.

Ultimately I think the argument here is about semantics - there are no "set in stone" definitions for compile, intepret, script and scripting.

Regardless of that if you think about what happens during the process of (your definition) of compile and (your definition) of intepretation you will see that the same thing is happening.

A utility takes a list of instructions, looks up the instuctions in a table. The table holds details of what machine code is required to complete that instruction.

What happens to the machine code is where the distinction lies - in a "compiled" language the utility writes then to a file, in an "interpreted" language the utility sends them to the CPU to be run immediately. But ultimately the instructions have gone through the same process.

Now if we introduce optimisation - then the compiler, because it is able to analyse the instructions in their entirety, prior to execution, is more able to take decisions on what would be more efficient based on how the code works as a whole.

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Originally posted by CornedBee
The third definition is quite vague (what is computer-readable?), so I'll ignore it. But the second definition exactly matches what I mean. Compilation means that pieces of machine code are put together to form code. In interpretation, the pieces are not put together, they are called in succession, but always will the interpreter itself be there in-between.

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And what is the difference between the interpreter being in-between and the compiler being in-between?

Is Slaine Arc's twin brother or something? Jeeze, you two have alot of reading to do.

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Originally posted by CornedBee
Slow down kas.

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He deserved it, coming into a thread making ignorant comments about PHP and then saying he was a PHP Professional.

Come on, that is just asking for a flame.

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Originally posted by kasracer
Is Slaine Arc's twin brother or something? Jeeze, you two have alot of reading to do.

He deserved it, coming into a thread making ignorant comments about PHP and then saying he was a PHP Professional.

Come on, that is just asking for a flame.

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It seems to me kasracer you're only contribution to the discusion is to bandy insults and put downs. Is this to disguise your lack of knowledge on the subject, or are you just incapable of reasoned debate.

Don't waste your time answering me cause you are now on my ignore list.

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Originally posted by Slaine
It seems to me kasracer you're only contribution to the discusion is to bandy insults and put downs. Is this to disguise your lack of knowledge on the subject, or are you just incapable of reasoned debate.

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I've been in plenty of debates, but come on now. What you two are arguing for isn't even remotely true and is just plain stupid. There is no point. That and this is chit chat, if you actually wanted a debate on something, you wouldn't post it here because all I do here is bull****, as well as most people.

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Originally posted by Slaine
Don't waste your time answering me cause you are now on my ignore list.

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Congradulations, you can't take an insult from someone on the internet and put them on your ignore list. Grow some thicker skin, wuss.

In my opinion you are taking this debate too seriously kasracer. All you are doing is replying to posts and saying they are wrong and not backing up your reasons:confused:

I think by now most readers of this thread have concluded that there is a fine line in how we define a compiled an interpreted language and their exact definitions.

At the end of the day even the CPU must interpret the machine code and carry out a predefined action based on the instruction given.

If you take Java as an example, it is compiled into intermediate code before being interpreted by a JVM on the clients machine.

Visual Basic executables use VB runtime libraries to convert a type of intermediate machine code into real machine code.

Both these beg the question - Compiled or Interpreted?

Interesting thread though I've learnt alot from reading it:wave:

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Originally posted by visualAd
All you are doing is replying to posts and saying they are wrong and not backing up your reasons

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Originally posted by visualAd
In my opinion you are taking this debate too seriously kasracer.

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Does not compute. How exactly would that be serious?

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Originally posted by kasracer
Does not compute. How exactly would that be serious?

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You Tell Me:)

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Originally posted by Slaine
For the time being let us ignore any optimistation that may take place during any kind of interpretation/compilation. I am also not denying that pre-processed code is different to code processed on the fly.

Ultimately I think the argument here is about semantics - there are no "set in stone" definitions for compile, intepret, script and scripting.

Regardless of that if you think about what happens during the process of (your definition) of compile and (your definition) of intepretation you will see that the same thing is happening.

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None of this contradicts what I said.
I know that essentially the same thing happens, and I acknowledged it in my last post (though not very obviously), but the difference is in the fine points of how and when it is done. You say pre-processed code is different to code processed on the fly, and this is what this debate is about. The former is compiled, the latter interpreted. And PHP is interpreted, the code is processed on the fly.

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A utility takes a list of instructions, looks up the instuctions in a table. The table holds details of what machine code is required to complete that instruction.

What happens to the machine code is where the distinction lies - in a "compiled" language the utility writes then to a file, in an "interpreted" language the utility sends them to the CPU to be run immediately. But ultimately the instructions have gone through the same process.

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A file or some memory location - see JIT compiling.

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And what is the difference between the interpreter being in-between and the compiler being in-between?

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The interpreter is in-between on every execution, the compiler is in-between only during compile, never during execution.