read.and.check
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.
- Keywords
- utilities
Usage
read.and.check(message = "", what = numeric(), lower, upper, answer.in,
default)
Arguments
- message
message displayed before prompting for user input.
- what
the type of
what
gives the type of data to be read.- 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
answer.in
, if supplied.- default
value assumed if user enters a blank line.
Value
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
.
Note
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.