`DTABase::checkStr`

Checks if string $input contains the expected value at an offset.

       require_once '/DTABase.php';

         boolean
         DTABase::checkStr

         string
         $input

         integer
         &$offset

         string
         $expected

&title.desc;

After the check the offset is increased.

&title.param;

&type.string; `$input`

- string to check

&type.int; `&$offset`

- current offset into input

&type.string; `$expected`

- expected string at the offset

&title.returns;

returns true if input is as expected, otherwise an exception is thrown

&title.throws;

throws Payment_DTA_Exception if input differs from expected string

&title.note; ¬e.notstatic;