Backslash confusion

F

freelance71

I have to pass the string '\abcd' to a function. Ofcourse one (or two) extra
'\' is needed to escape but experimenting with it shows that I have to pass
three extra backslashes to make it work.

<script>
var q = "\\\\abcd";
displayLatex(q);
</script>


/* this function is in another file */

function displayLatex(q) {


alert(q); /* this shows \abcd when called by above script*/

}


Can anyone explain why this is so? why 4 backslashes?
 
E

Erwin Moller

freelance71 schreef:
I have to pass the string '\abcd' to a function. Ofcourse one (or two) extra
'\' is needed to escape but experimenting with it shows that I have to pass
three extra backslashes to make it work.

<script>
var q = "\\\\abcd";
displayLatex(q);
</script>


/* this function is in another file */

function displayLatex(q) {


alert(q); /* this shows \abcd when called by above script*/

}


Can anyone explain why this is so? why 4 backslashes?
Click to expand...

I do not understand.
Your script alerts \\abcd over here (on FF), as expected.
There must be more to it than you describe.

Regards,
Erwin Moller
 
F

freelance71

"Erwin Moller"
freelance71 schreef:

I do not understand.
Your script alerts \\abcd over here (on FF), as expected.
There must be more to it than you describe.

Regards,
Erwin Moller
Click to expand...


can it be because I'm using it in a PHP file like this?

<?php

echo <<< HTMLOUT

<script>

var q = '\\\\abcd';

displayLatex(q);

</script>

HTMLOUT;

?>
 
E

Erwin Moller

freelance71 schreef:
"Erwin Moller"



can it be because I'm using it in a PHP file like this?
Click to expand...

Yes. That is the reason.
<?php

echo <<< HTMLOUT

<script>

var q = '\\\\abcd';
Click to expand...

that becomes:
var q = '\\abcd';

in your HTML.
Simply check your source in your browser to see it.

Regards,
Erwin Moller
 
T

Thomas 'PointedEars' Lahn

freelance71 said:
freelance71 schreef:
Click to expand...
[...]
can it be because I'm using it in a PHP file like this?

<?php

echo <<< HTMLOUT

<script>

var q = '\\\\abcd';

displayLatex(q);

</script>

HTMLOUT;

?>
Click to expand...

Yes, you have to escape each backslash for use with `echo'. A simple test
(with php -a) shows that

<?php

echo <<<HTML

var q = '\\a';

HTML;

?>

displays only one backslash.

The simple and most efficient solution is to take heed of this general
advice: Do not let the PHP parser do things it does not have to.

<?php
...
?>
var q = '\\a';
<?php
...
?>

(The first and last part are optional, of course.)


F'up2 cl.php

PointedEars
 

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