Read data interactively and check that it satisfies conditions
Input is read interactively and checked against conditions specified
by the arguments what
, lower
, upper
and
answer.in
. If the input does not satisfy all the conditions,
an appropriate error message is produced and the user is prompted
to provide input. This process is repeated until a valid input value
is entered.
read.and.check(message = "", what = numeric(), lower, upper, answer.in, default)
message |
message displayed before prompting for user input. |
what |
the type of |
lower |
lower limit of input, for numeric input only. |
upper |
upper limit of input, for numeric input only. |
answer.in |
the input must correspond to one of the elements of the
vector |
default |
value assumed if user enters a blank line. |
The value of the valid input. When the default
argument is
specified, a blank line is accepted as valid input and in this case
read.and.check
returns the value of default
.
Since the function does not return a value until it receives valid input, it extensively checks the conditions for consistency before prompting the user for input. Inconsistent conditions will cause an error.
Martyn Plummer
Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.