rtrim函数在此代码中不起作用

need not comma operator[,] when I used others check box with empty input fields. rtrim function is not working here,

My code

 $compydomain=$this->input->post('companydomain');//get values from                       checkboxes
   if(isset($compydomain)){
    $domains=implode(',', $compydomain);  
    if($domains == 'others'){
        $domaintext=  $this->input->post('companydomaintext');
    }else if($domains == TRUE && $this->input->post('companydomaintext')== TRUE){
        $words = explode( ",", $domains );
        array_splice( $words, -1 );
        $res= implode( " , ", $words );
        $domaintext1 = $res." , " .$this->input->post('companydomaintext'); 
        $test=substr("$domaintext1",-1);
        if($test==",")
        {
            $domaintext=rtrim($domaintext1,",") ;
        }
       else {
        $domaintext=$domaintext1;
          }
        // Concate two values
       }else{
       $domaintext=$domains;
        //$domaintext=  $this->input->post('companydomaintext');
    }



}

You want to use explode instead of rtrim.
Change code to:

$domaintext=explode(',',$domaintext1) ;