8.2 Prompting for values

8.2.2 Prompting for integers

The CAPI also provides a number of more specific dialogs that allow you to enter other types of data. For example, to enter an integer, use the function prompt-for-integer. Only integers are accepted as valid input for this function.

(prompt-for-integer
 "Enter an integer:")

There are a number of extra options which allow you to specify more strictly which integers are acceptable. Firstly, there are two arguments:min and:max which specify the minimum and maximum acceptable integers.

(prompt-for-integer
 "Enter an integer:"
 :min 10 :max 20)

If this does not provide enough flexibility you can specify a function that validates the result with the keyword argument:ok-check. This function is passed the current value and must return non-nil if it is a valid result.

(prompt-for-integer
 "Enter an integer:"
 :ok-check 'oddp)

CAPI User Guide, Liquid Common Lisp Version 5.0 - 2 OCT 1997

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