variable with NULL value

Hi,

one more question.

Why the variable, that contains NULL value appears to be not set. When
you try to echo it the php does not produce warning about using
undefined variable.

//$connection contains database connection handler
$result=mysql_query("select NULL as value",$connection);
$tmp=mysql_fetch_array($result);
$foo=$tmp["value"];
if (!isset($foo)) echo("\$foo is not set but does not produce warning
-$foo-");

OKi98

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Re: variable with NULL value

OKi98 wrote:
> Hi,
>
> one more question.
>
> Why the variable, that contains NULL value appears to be not set. When
> you try to echo it the php does not produce warning about using
> undefined variable.
>
> //$connection contains database connection handler
> $result=mysql_query("select NULL as value",$connection);
> $tmp=mysql_fetch_array($result);
> $foo=$tmp["value"];
> if (!isset($foo)) echo("\$foo is not set but does not produce warning
> -$foo-");
>
> OKi98
>
Someone correct me if I'm wrong but it appears that you should be using
if(!isset($tmp["value"]) before assigning to $foo if you want to ensure
that $foo will, indeed, be set.

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Thanks,

Jim

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Re: variable with NULL value

James Gadrow wrote:
> OKi98 wrote:
>> Hi,
>>
>> one more question.
>>
>> Why the variable, that contains NULL value appears to be not set. When
>> you try to echo it the php does not produce warning about using
>> undefined variable.
>>
>> //$connection contains database connection handler
>> $result=mysql_query("select NULL as value",$connection);
>> $tmp=mysql_fetch_array($result);
>> $foo=$tmp["value"];
>> if (!isset($foo)) echo("\$foo is not set but does not produce warning
>> -$foo-");
>>
>> OKi98
>>
> Someone correct me if I'm wrong but it appears that you should be using
> if(!isset($tmp["value"]) before assigning to $foo if you want to ensure
> that $foo will, indeed, be set.

Yeh - you need to check before you do the assignment.

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RE: variable with NULL value

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