How to find if a number is odd or even?
In PHP I learn to use the MOD (%) operator. see below for an example: $i = 10;

if ($i % 2) {
echo "$i is odd";
} else {
echo "$i is even";
}


You can also use the PHP “&” operator that will give you better performance
You can use the PHP code like so:

$i = 10;
if ( $i&1 )
{
echo "$i is odd";
}
else
{
echo "$i is even";
}

The function below checks if the content has the general syntax of an email.

This means that the input data must contain at least an @ sign and a dot (.). Also, the @ must not be the first character of the email address, and the last dot must at least be one character after the @ sign:

<script language="Javascript">
function checksubmit()
{
apos=document.add_data.email.value.indexOf("@")
dotpos=document.add_data.email.value.lastIndexOf(".")
if (document.add_data.email.value == "" || apos<1 || dotpos-apos<2)
{
alert("Please fix: email")
document.add_data.email.focus()
return false
}
return true
}
</script>