Rand() always generating same number

[DanC]

Hi,

 

I have this code in my script:

$genno=rand(1,50000000000000);
// Run some security checks for duplicate ids
$genids=mysql_query("SELECT gen FROM info WHERE gen='$genno' ");
$checkgenids=mysql_num_rows($genids);
while ($checkgenids > 0) {
	$genno=rand(1,50000000000000);
}
// End the check
$nameids=mysql_query("SELECT name FROM info WHERE name='$name' ");
$checknameids=mysql_num_rows($nameids);
if ($checknameids > 0) {
	die('<p><b><center><font color=red>Product name "'.$name.'" already exists!<hr></font></center></b></p>');
}
mysql_query("INSERT INTO $maintab ($nametab, $linktab, $comptab) VALUES('$name', '$link', '$comp')") or die(mysql_error());
mysql_query("INSERT into $gcodetab ($codetab) VALUES ('$finalshuffle')") or die(mysql_error());
mysql_query("UPDATE $gcodetab SET gen='$genno' WHERE gen='0'") or die(mysql_error());
mysql_query("INSERT into download (id, gen) VALUES ('$genno', '$genno')") or die(mysql_error());
mysql_query("UPDATE $maintab SET gen='$genno' WHERE gen='fill'") or die(mysql_error());
mysql_free_result();
mysql_close;

 

However, no matter how many times I run this code, it ALWAYS inserts the SAME number into the database. It works perfectly on localhost, but not when I upload it to my online host. I've asked them to check for any restrictions, but they showed me a test with rand function and it was working fine. Is it something in my code that is wrong? It inserts the random code into two tables in a database so I can match them up later, but one table always has the same code and the other table has a different code.

 

Help!

 

Thanks,

 

Dan.

[ILMV]

Try using mt_rand() instead...

[Mark Baker]

Whether using rand or mt_rand, the result is an integer value so it is limited by the maximum integer value. 50000000000000 is way, way above this value.

Use getrandmax() or mt_getrandmax() to identify the upper limit of random numbers on your platform

 

[Dtonlinegames]

Looks to me like $genno is set outside of a loop, so its set once and the number will always be more than 0 as you check here and therefore never actually changes

 

while ($checkgenids > 0) {
	$genno=rand(1,50000000000000);
}

 

So you might want to put something at the end of you're code

 

either

 

$genno='';

 

Or doing a do{}while()

 

like

 

do{

$genno=rand(1,50000000000000);
// Run some security checks for duplicate ids
$genids=mysql_query("SELECT gen FROM info WHERE gen='$genno' ");
$checkgenids=mysql_num_rows($genids);
while ($checkgenids > 0) {
	$genno=rand(1,50000000000000);
}
// End the check
$nameids=mysql_query("SELECT name FROM info WHERE name='$name' ");
$checknameids=mysql_num_rows($nameids);
if ($checknameids > 0) {
	die('<p><b><center><font color=red>Product name "'.$name.'" already exists!<hr></font></center></b></p>');
}
mysql_query("INSERT INTO $maintab ($nametab, $linktab, $comptab) VALUES('$name', '$link', '$comp')") or die(mysql_error());
mysql_query("INSERT into $gcodetab ($codetab) VALUES ('$finalshuffle')") or die(mysql_error());
mysql_query("UPDATE $gcodetab SET gen='$genno' WHERE gen='0'") or die(mysql_error());
mysql_query("INSERT into download (id, gen) VALUES ('$genno', '$genno')") or die(mysql_error());
mysql_query("UPDATE $maintab SET gen='$genno' WHERE gen='fill'") or die(mysql_error());
mysql_free_result();
}
while($genno!==$genno);
mysql_close;

 

That will loop that entire function as long as Genno DOESNT equal its last value

 

I havent tested this but it seemed the only option, I had a similar problem once. Many moons ago