Use of increment operator in heredoc
Use of increment operator in heredoc
I want to increase the value of a variable by using the increment operator in heredoc. My current code is given below...
$counter = 0;
for($i = 0; $i<10; $i++):
echo <<< EOT
$counter++ <br/>
EOT;
endfor;
Its output is...
0++
0++
.
.
Mean post-increment operator is not working.
I have also tried pre-increment, like given below...
echo <<< EOT
++$counter <br/>
EOT;
Its output is...
++0
++0
.
.
Mean pre-increment operator is also not working.
I have also tried to put increment operation inside curly braces, like given below...
echo <<< EOT
++$counter <br/>
EOT;
But again no luck. Output is....
++0
++0
.
.
I have also searched it on google but didn't find anything useful.
I know if I can increase value before heredoc then I can print it in here doc correctly
$counter = 0;
for($i = 0; $i<10; $i++):
++$counter;
echo <<< EOT
$counter <br/>
EOT;
endfor;
It works fine.
But I want to use increment operator in heredoc, just like we use in case of single or double quoted with echo.
echo
But it seems like heredoc doesn't support increment operation.
$var
$countupfunc($counter)
$i
So, you found out that heredoc does not support incrementing variables. Do you have a question?
– u_mulder
Sep 12 '18 at 6:52
No, I didn't find it. I supposed it for now.
– Shujaat
Sep 12 '18 at 6:53
@mario I can use
$i, but proper name increase readability of code.– Shujaat
Sep 12 '18 at 6:54
$i
1 Answer
1
The complex/curly variable syntax $var… does only allow variable access expressions, but not PHP expressions per se.
$var…
$var[…]
$var(…)
$var->prop…
$stat::$lookup
There can't be arithmetic operators within the + itself. But only between […] or (…) used alongside.
[…]
(…)
One common workaround is to utilize variable function names:
$func = "htmlspecialchars"; // or any other no-op function
echo <<<HEREDOC
counter = $func($counter++)
HEREDOC;
Where you can easily use full expressions in the curly var syntax.
"There can't be arithmetic operators within the + itself. But only between […] or (…) used alongside." Can you please provide any reference?
– Shujaat
Sep 12 '18 at 7:02
See the manual link. Though it's only described with more examples there, it lists the various allowed expressions.
– mario
Sep 12 '18 at 7:04
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$varworks really just for limited variable access expressions. Something like$countupfunc($counter)e.g. Albeit this looks like an abstracted example, couldn't you just use$ianyway?– mario
Sep 12 '18 at 6:50