validating using php

thanks to everyone for providing the solution for validating textarea using
php i have used the following and it worked

$add = trim($_POST["add"]);

if(strlen(trim($add)) == 0 )
{
$error.="<br>Please enter your address ";
}


as part of the form the user has to fill in their name, assuming if the user
simply presses the space bar i would like to display a message like the text
area. presently my validation for name is

$name = trim($_POST["name"]);

if( strlen(trim($name) == 0 ) || !preg_match('/^[a-zA-Z ]+$/x', $name) )
{
$error.="Name is blank or has special characters ";
}

with the above code for validating the name if a user types only spaces then
the error message is displayed however if there is a gap in the name example
john smith the error message is appearing which should not be happening as i
have given
preg_match('/^[a-zA-Z ]+$/x', $name) which means the user can type small,
upper case letters and also there can be a space in the name

how can i change the php code = if( strlen(trim($name) == 0 ) ||
!preg_match('/^[a-zA-Z ]+$/x', $name) )

so that i can validate both a) blank spaces and also accept spaces between
the name, i can validate individually for spaces and uses preg_match as 2
separate lines, instead i would like to validate in a single line of php

please advice.

thanks.