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PHP: Do you know basic syntax?


PHP: Do you know basic syntax?  

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Question

balupton

It seems that a lot or even most php programmers just jumped in and never read the manual or even know basic syntax...

The ones I see all the time are:

Not checking variable existence by just doing

$param = $_GET['param'];

instead of the correct

$param = isset($_GET['param']) ? $_GET['param'] : NULL;

which will not return a notice exception

Reference: http://au3.php.net/manual/en/language.variables.php

Using short tags

<?

instead of the proper

<?php

which will run on many more servers

Reference: http://php.net/manual/en/language.basic-syntax.php

Also the misuse of double quotes

$var = "hello";

should be

$var = 'hello';

which saves processing time

Reference: http://php.net/manual/en/language.types.st...g.syntax.single

Those are just some of the most common ones.

So what i'm asking is:

Why didn't you know this stuff if you didn't before hand?

Or if you did know this, then why do you think things like this are so ignored?

Note:

The option "I thought I did until now." should read "No, I'm a professional developer."

The option "No." should read "No, I'm a unprofessional developer."

-------------------

This thread has kinda turned into a tips thread, so here are a collection of tips that have been collected so far.

Single quotes vs Double quotes

$var = 'hello';
$string = '$var is '.$var;
// is faster than
$var = 'hello';
$string = "\$var is $var";

http://www.neowin.net/forum/index.php?show...amp;p=588249172

Switch statements VS if then else statements

switch ($var)
{
   case $option1:
	  break;
   case $option2:
	  break;
   default:
	  break;
}
// is faster than
if ( $var == $option1 )
{ }
elseif ( $var == $option2 )
{ }
else
{ }

Thanks to redFX for reminding us of that:

http://www.neowin.net/forum/index.php?show...amp;p=588271991

If then else statements VS ternary statements

if ( false )
{ echo 'true'; }
else
{ echo 'false'; }
// if faster than
echo (false ? 'true' : 'false');
// which is faster than
echo false ? 'true' : 'false';

Also applies for $var =, instead of echo. Thanks to redFX for that:

http://www.neowin.net/forum/index.php?show...amp;p=588271991

Pre-Increment VS Post-Increment

++$i;
// is faster than
$i++;

This applies everywhere, so in for loops etc. Thanks to phpmozzer for that:

http://www.neowin.net/forum/index.php?show...amp;p=588271806

Loops in order of speed

for, foreach, while, do-while. Thanks to redFX for that:

http://www.neowin.net/forum/index.php?show...amp;p=588271808

Strict (===) comparison is faster than loose (==) comparison.

http://www.neowin.net/forum/index.php?show...amp;p=588271983

Instantiating classes

$Class = & new Class();
// is faster than
$Class = new Class();

Thanks to http://www.php.lt/benchmark/phpbench.php

For loops and size calculations

for ( $i = 0, $n = sizeof($array); $i < $n; $i++ ) {}
// is faster than
for ( $i = 0; $i < sizeof($array); $i++ ) {}

http://www.neowin.net/forum/index.php?show...amp;p=588249623

Variable declarations and memory

$var1 = 'hello';
$var2 = $var1; // In C the variable var2 is created in memory right here
$var2 = 'bye'; // In PHP the variable var2 is created in memory here, up until now it still uses the same location of memory as var1

So in general, references should only be used if you want to work with the original variable, as it does not save memory or processing time.

http://www.neowin.net/forum/index.php?show...amp;p=588249172

If you know any others, feel free to post them :)

Edited by balupton
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balupton

Yeah still seems illogical to me... ;) I'm benchmarking it now to see what happens...

And instead of

if ($test1 == $test2) echo 'Yes'; else echo 'no';

you could use the better option of

echo $test1 == $test2 ? 'Yes' : 'no';

:)

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balupton

Yeah, my benchmarks agree :)

Dummy Test:

0.00022300s

For Loop (Post-Increment):

0.00023600s

For Loop (Pre-Increment):

0.00017100s

Loose Comparison:

0.00047200s

Strict Comparison:

0.00030000s

Each loop goes through 1000 iterations.

benchmarks.zip

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redFX
Yeah still seems illogical to me... ;) I'm benchmarking it now to see what happens...

And instead of

if ($test1 == $test2) echo 'Yes'; else echo 'no';

you could use the better option of

echo $test1 == $test2 ? 'Yes' : 'no';

:)

Ahh yes, here's a good tip... using the first one is faster then the second one.

I just ran a benchmark on them both and the first one (with the if statement) is a full second faster then the second one (when running them each 5 million times).

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balupton

// ---------------------
// Test 5
echo "\r\n".'If Else Comparison: '."\r\n";

$T->start();

for ( $i = 0, $n = 1000; $i < $n; ++$i )
{
	if ( false )
	{ true; }
	elseif ( true )
	{ false; }
}

$T->stop();

// ---------------------
// Test 6
echo 'Ternary Comparison: '."\r\n";

$T->start();

for ( $i = 0, $n = 1000; $i < $n; ++$i )
{
	false ? true : false;
}

$T->stop();

// ---------------------

Gives

If Else Comparison:

0.00028000s

Ternary Comparison:

0.00024100s

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phpmozzer

1. true == true Took 3

2. true === true Took 2

3. 'Hello' == 'Hello' Took 5

4. 'Hello' === 'Hello' Took 2

Output comes from

<?php
$loop = 10000000;
$time = time();
for ( $i = 1; $i <=$loop; ++$i )
{
	if ( true == true ) 
	{ }
}
$end = time() - $time;
echo "1. true == true Took $end\n";

$time = time();
for ( $i = 1; $i <=$loop; ++$i )
{
	if ( true === true )
	{}
}
$end = time() - $time;
echo "2. true === true Took $end\n";

$time = time();
for ( $i = 1; $i <=$loop; ++$i )
{
	if ( 'Hello' == 'Hello' ) 
	{ }
}
$end = time() - $time;
echo "3. 'Hello' == 'Hello' Took $end\n";

$time = time();
for ( $i = 1; $i <=$loop; ++$i )
{
	if ( 'Hello' === 'Hello' )
	{}
}
$end = time() - $time;
echo "4. 'Hello' === 'Hello' Took $end\n";
?>

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balupton

Hrmm, using

// ---------------------
// Test 5
echo "\r\n".'If Else Comparison: '."\r\n";

$T->start();
ob_start();

for ( $i = 0, $n = 1000; $i < $n; ++$i )
{
	if ( false )
	{ echo 'true'; }
	else
	{ echo 'false'; }
}

ob_end_clean();
$T->stop();

// ---------------------
// Test 6
echo 'Ternary Comparison: '."\r\n";

$T->start();
ob_start();

for ( $i = 0, $n = 1000; $i < $n; ++$i )
{
	echo false ? 'true' : 'false';
}

ob_end_clean();
$T->stop();

// ---------------------

Gives

If Else Comparison:

0.00031100s

Ternary Comparison:

0.00041700s

Which is the opposite to what i posted above, seems that the echo makes a big difference.

Edit: Actually it is not the echo that cause the change, it was the use of strings, eg. echo 'true' instead of echo true. So thanks for that redFX :D

Edited by balupton
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phpmozzer

I was going to post the results from when comparasons fail ie

if ( true === false ) {} etc, but it comes out exactly the same

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phpmozzer

I carried them out as well ( see above ). Quite an interesting topic ( Might write about it on my blog ( what a sad thing to say - "Thats cool, lets blog it" ) ).

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balupton

Hehe yeah :)

I'll stick it on my blog as well, and in some other forums i'm a part of. I learnt a fair few things today because of it :)

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phpmozzer

I haven't learnt anything but it has reminded me again of the importance of performance as a test for experience in coders

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balupton
Variable declarations and memory

$var1 = 'hello';
 $var2 = $var1; // In C the variable var2 is created in memory right here
 $var2 = 'bye'; // In PHP the variable var2 is created in memory here, up until now it still uses the same location of memory as var1

So in general, references should only be used if you want to work with the original variable, as it does not save memory or processing time.

http://www.neowin.net/forum/index.php?show...amp;p=588249172

Regarding that, I've just run some benchmarks, and it seems that if say $var1 = $array['hello'], then references are faster! For both reading and setting!

Check out the last section of the attached php file for the benchmarks.

benchmarks.zip

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+mrbester

Point of note: This thread isn't about syntax, which is purely how a block of code is structured (in other words, do you know how to write a "sentence" or "paragraph" in this language?), but refactoring.

Edit: The original post (first example) is an example of differences in variable aquisition: In ASP setting a variable to a (non-existent) querystring key's value results in a zero length string (the same as if the key did exist, but the value wasn't set), whereas in .NET and PHP it results in a NULL (or possibly even errors out), which is a different variable type.

ASP does not have an equivalent isset() function. You have to write one yourself... ;)

Edited by mrbester
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gigapixels

goto.png

:whistle:

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