(PHP 4 >= 4.0.2, PHP 5)
mcrypt_module_is_block_algorithm — This function checks whether the specified algorithm is a block algorithm
$algorithm
   [, string $lib_dir
  ] )
   This function returns TRUE if the specified algorithm is a block
   algorithm, or FALSE if it is a stream one.
  
algorithmThe algorithm to check.
lib_dir
       The optional lib_dir parameter can contain the
       location where the algorithm module is on the system.
      
   This function returns TRUE if the specified algorithm is a block
   algorithm, or FALSE if it is a stream one.