This predicate checks if the character argument is a control character, for example: the tab character. It succeeds if this is so, else it fails.
see also: &/2 delete/3 insert/3 is/2 is_alpha/1 is_alphanum/1 is_ascii/1 is_digit/1 is_graph/1 is_lower/1 is_upper/1 is_space/1 substring/3 string_list/2 working with strings
| Examples | |
| is_cntrl('\t'). | succeeds because the tab character is a control character |
| is_cntrl(a). | fails because a is not a control character |
| Exceptions | |
| The parameter is an empty variable | an instantiation_error exception is thrown |
| The parameter is a list | a type_error(character, Arg) exception is thrown and Arg is replaced by the value of the parameter |
| The parameter is an integer that exceeds the specified range of integers | an evaluation_error(int_overflow) exception is thrown |
| The parameter is not a correct character | a type_error(character, Arg) exception is thrown and Arg is replaced by the value of the parameter |