comment block php code example

Example 1: php comment

// This is a single-line comment

# This is also a single-line comment

/*
This is a multiple-lines comment block
that spans over multiple
lines
*/

Example 2: php comment

<?php
// This is a single-line comment

# This is also a single-line comment
  
/*
This is a multiple-lines comment block
that spans over multiple
lines
*/
  
// You can also use comments to leave out parts of a code line
$x = 5 /* + 15 */ + 5;
echo $x;
?>

Example 3: comment in php

A nice way to toggle the commenting of blocks of code can be done by mixing the two comment styles:
<?php
//*
if ($foo) {
  echo $bar;
}
// */
sort($morecode);
?>

Now by taking out one / on the first line..

<?php
/*
if ($foo) {
  echo $bar;
}
// */
sort($morecode);
?>
..the block is suddenly commented out.
This works because a /* .. */ overrides //. You can even "flip" two blocks, like this:
<?php
//*
if ($foo) {
  echo $bar;
}
/*/
if ($bar) {
  echo $foo;
}
// */
?>
vs
<?php
/*
if ($foo) {
  echo $bar;
}
/*/
if ($bar) {
  echo $foo;
}
// */
?>

Example 4: comments in php

//For a single line comment use //:
//this is a comment too
//for multi-line comments use /* and */:
/* <--start of multi-line comment
this is a comment

this is a comment too (end of multi-line comment)-->*/

Example 5: comment in php

it's perhaps not obvious to some, but the following code will cause a parse error! the ?> in //?> is not treated as commented text, this is a result of having to handle code on one line such as <?php echo 'something'; //comment ?>

<?php
if(1==1)
{
    //?>
}
?>

i discovered this "anomally" when i commented out a line of code containing a regex which itself contained ?>, with the // style comment.
e.g. //preg_match('/^(?>c|b)at$/', 'cat', $matches);
will cause an error while commented! using /**/ style comments provides a solution. i don't know about # style comments, i don't ever personally use them.