Hi,

Can someone tell me why this little piece of php/mysql code fails?

$row = $result->fetch_assoc();

if ($clog)
fwrite($logfile,"row['nametag'] {$row['nametag']}\n");

if ($row['nametag'] != 0) {
if ($clog)
fwrite($logfile,"name {$row['nametag']}\n");
}


I've got this logfile where I am putting debug output. In the above, the
first fwrite works -- it writes the name contained in the row value
'nametag'.

But then, when I test that same value for nonzero, it fails? If never
prints that second line. Why should $row['nametag'] fail the != 0 test?

Thanks
Bob

On 26.09.2011 18:08, Bint wrote:
if ($row['nametag'] + 0)

On 26.09.2011 18:08, Bint wrote:

No, it's a string. If I just use
If ($row['nametag']) {

then it works. But it is just extremely counterintuitive that that != 0
test should fail. It is stuff like that that is always tripping me up in
PHP.

Thanks
Bob

Bint wrote:
weakly typed languages eh?

where '0'=0 !!!

On 26.09.2011 18:44, Bint wrote:
to check here. You should always write EXACTLY what you test for, and
here you're not checking if the string is nonzero. And non-numeric
string equals zero.

But not even that! Where 'I am a string' == 0!
I was just trying to check whether the string was NULL or not basically, and
it IS counterintuitive to me at least that a string with something in it
would equate to 0.

Bob

Bint wrote:
I tend to use (strlen($string)==0)

Or ($string == "")..

Well like I said,

if ($string)

is fine as long as it works, and it seems to work. I just cannot believe
that

if ($string)

does not give the same result as

if ($string != 0)

Bob

On Mon, 26 Sep 2011 21:04:05 +0100, The Natural Philosopher wrote:
Don't chop wood with a shovel. There's a right way to do this.

$ cat foo.php
<?php

echo "Test #1\n";

if (empty($string)) {
echo "not set, 0, 0.0, '' but not ' ', etc.\n";
if (! isset($string)) {
echo "not set at all\n";
}
}

echo "Test #2\n";

$string = 0;

if (empty($string)) {
echo "not set, 0, 0.0, '' but not ' ', etc.\n";
if (! isset($string)) {
echo "not set at all\n";
}
}

echo "Test #3\n";

$string = '';

if (empty($string)) {
echo "not set, 0, 0.0, '' but not ' ', etc.\n";
if (! isset($string)) {
echo "not set at all\n";
}
}

echo "Test #4\n";

$string = ' ';

if (empty($string)) {
echo "not set, 0, 0.0, '' but not ' ', etc.\n";
if (! isset($string)) {
echo "not set at all\n";
}
}

?>
$ php -f foo.php
Test #1
not set, 0, 0.0, '' but not ' ', etc.
not set at all
Test #2
not set, 0, 0.0, '' but not ' ', etc.
Test #3
not set, 0, 0.0, '' but not ' ', etc.
Test #4
$

--
2. My ventilation ducts will be too small to crawl through.
--Peter Anspach's list of things to do as an Evil Overlord