validate-readln ( -- str )

Vocabulary

rosetta-code.bulls-and-cows

Inputs

None

Outputs

str

an object

Definition

USING: io kernel ;

IN: rosetta-code.bulls-and-cows

: validate-readln ( -- str )
    readln dup (validate-readln) [
        "Invalid input.\nPlease enter a valid 4 digit number: "
        write flush drop validate-readln
    ] when ;