The inputnull statement is used with the input @ statement to define the character used to indicate a null input on subsequent input statements.
inputnull ’character’
| character | Character to define as the indicator of null input for subsequent input statements. Only single character inputs are accepted. |
The inputnull must precede the affected input @ statement. Only one inputnull statement is active at any one time. If there is an inputtrap active for the same character, the inputnull has precedence.
The input @ statement requires a numeric value for string. An x, although not numeric, is accepted as a null input.
string=’’ inputnull ’x’ input @(10,10):string,50 "mr%3" if string=’’ then stop
Even though the inputtrap reads x as an active value, the inputnull overrides. x does not terminate this program.
string=’’ inputtrap ’x?!’ gosub statement.label1,statement.label2,statement.label3 loop inputnull ’x’ input @(3,5):string,20 "mr#4" while string=’’ do repeat