[RESOLVED] Print, echo and semantics

phpSimon

Hi all

I often use a print statement during debug like this:

print ("Variable1: ".$variable1."<br />Variable2: ".$variable2."<br />");

Then I read that concatenation slows the process down, and that I should replace the periods with commas.

Then I found that this works anyway:

print("Variable1: $variable1 <br /> Variable2: $variable2 <br />");

It seems to me the latter would be most efficient for PHP. It's certainly the fastest to type and easiest to read in the IDE.

Both print and echo are language constructs and the PHP manual says it doesn't matter which I use; it's down to personal preference. There's a small difference in performance between echo and print, but that for something as simple as the above it wouldn't make any difference.

What do the experts feel is is the most semantically correct in the above print statements - or would you use echo instead? It's one less keypress, after all...

Thanks

bradgrafelman

I personally feel that either are fine. Even if there did happen to be a performance increase, it's going to be so insignificant that it wouldn't matter anyway.

phpSimon

Thanks!

Any other comments welcome - as it's a bit of a subjective topic I'll hold off resolving the thread in case there are other opinions but I expect they'll be the same, or similar.

laserlight

phpSimon wrote:
Then I read that concatenation slows the process down, and that I should replace the periods with commas.

That actually won't work with print. You can use this "micro-optimisation" with echo, but the difference is negligible.

phpSimon wrote:
It seems to me the latter would be most efficient for PHP. It's certainly the fastest to type and easiest to read in the IDE.

It is less efficient since variable interpolation requires the string literal to be parsed for those variables, and then the contents of those variables inserted in the middle of the string. On the other hand, it can sometimes make the string literal more readable.

phpSimon wrote:
Both print and echo are language constructs and the PHP manual says it doesn't matter which I use; it's down to personal preference. There's a small difference in performance between echo and print, but that for something as simple as the above it wouldn't make any difference.

Yes, plus if these are for debugging, then it really makes no difference whatsoever.

phpSimon

Thanks again!

When I'm printing to a page (and not for debugging) I normally use print.

Some of my work results in large tables of data but the time it takes to get that data from a remote MS SQL server is much longer than the time it takes to display it, so I'm not overly concerned with performance of the print command itself.

However, I am interested in programming as correctly as possible - so gathering together the advice so far it would seem in this case:

1) print with concatenation is how I'm doing it now
2) I could micro-optimise with echo and commas for a negligable efficiency improvement

I guess I could use echo when debugging to differenciate from non-debug code, but other than that, there's no real need to change.

Thanks for your input, much appreciated.

laserlight

phpSimon wrote:
I guess I could use echo when debugging to differenciate from non-debug code, but other than that, there's no real need to change.

One thing you may be able to do is to use a debugger instead of debug print statements. You could also use assertions to document certain assumptions and invariants: it would be better than checking the output of a debug print statement to see if the assumption holds true.

phpSimon

Yes, I've only recently moved to a proper IDE from a simple editor for PHP but I haven't got as far as debugging yet (I'm using Eclipse).

I didn't know about assertions though (here, for anyone else reading the thread).

I'll read up.

Thanks.