Regular expression help

[mrithula]

I need regular expression to validate the following input

possible inputs:

sin(x)+cos(x)

cos(x)-sin(x)

sin(x)-cos(x)

 

Error shoud be displayed if any other character except sin(x),cos(x),+ and - is used

 

can some one help me?

[wildteen88]

Basic regex pattern

~(cos|sin)\([a-z0-9\.]+\)[+-](cos|sin)\([a-z0-9\.]+\)~

 

Test code

$strings = array( 'sin(x)+cos(x)',
                  'cos(x)-sin(x)',
                  'sin(x)-cos(x)',
                  'sin(x)*cos(x)',
                  'sin(x)/cos(x)',
                  'sin(x)+sin(x)',
                  'cos(x)+cos(x)',
                );  

foreach($strings as $string)
{
    preg_match('~(cos|sin)\([a-z0-9\.]+\)[+-](cos|sin)\([a-z0-9\.]+\)~', $string , $matches);
    
    echo $string . ' - ' . ( isset($matches[0]) && ($matches[1] != $matches[2]) ? 'PASS' : 'FAIL' ) . '<br />';
}