mysql_fetch_object() confusion

[frijole]

<?php
mysql_connect("hostname", "user", "password");
mysql_select_db("mydb");
$result = mysql_query("select * from mytable");
while ($row = mysql_fetch_object($result)) {
    echo $row->user_id;
    echo $row->fullname;
}
mysql_free_result($result);
?>

 

In this code the mysql query is stored in the variable $result. Then, the while loop begins and its condition is:

while ($row = mysql_fetch_object($result)) 

 

$row was never set to TRUE. mysql_fetch_object($result) returns TRUE while there are still more rows matching the query, I think. So, how does this work? Am I missing something?

[Barand]

As long as there is a next row to fetch, $row is set to an object containing the row's field values.

 

At the end, when there are no more rows, mysql_fetch_object returns FALSE instead of an object.

[frijole]

I am confused as to what the condition of the while loop is, i.e. while (something) the following code is executed. What is the something?

[Barand]

"something" can be any expression returning a true or false result. As long as the expression evaluates to TRUE the loop executes

 

When converting to boolean, the following values are considered FALSE:

 

    * the boolean FALSE itself

    * the integer 0 (zero)

    * the float 0.0 (zero)

    * the empty string, and the string "0"

    * an array with zero elements

    * an object with zero member variables (PHP 4 only)

    * the special type NULL (including unset variables)

    * SimpleXML objects created from empty tags

 

Every other value is considered TRUE (including any resource).

[frijole]

ok, now that makes sense. So, $row = mysql_fetch_object($result) is not false (true) until it runs out of rows.

[Barand]

Exactly. Same goes for

 

mysql_fetch_row

mysql_fetch_array

mysql_fetch_assoc