How to preSelect an html dropdown list with php? [duplicate]

Answer 1

I have 2 php files and i made this, and it works. (this is an example) the first code is from the one file and the second code from two file.

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if(isset ($_POST['one']))
{

if($_POST['numbers']=='1')
{
$a='1' ;
}
else if($_POST['numbers']=='2')
{
$a='2' ;
{
else if ($_POST['numbers']=='3')
{
$a='3' ;
}

}