Question

Which example sets a constraint to validate user input?

A: The name field disallows numbers.
B: The email field accepts only numbers.
C: The address field should be less than 30 characters.
D: The zip code accepts letters.
E: The phone number accepts letters."

Answer 1

Option C: The correct example of a constraint for validating user input is C, where the address field is restricted to less than 30 characters. This limits input length, which is a common form of validation.

Step-by-step explanation:

The example that sets a constraint to validate user input is: C: The address field should be less than 30 characters. This is a typical form of input validation where the length of the input is restricted to ensure data fits within a predefined storage size or to meet certain usability standards. For instance, databases may allocate only limited character space for certain fields, making this validation essential.

Option A may also be considered a constraint, as it disallows numbers in the name field which is sensible since names typically consist of alphabetic characters. However, the limitation based on characters rather than length or format is more of a pattern restriction. The other examples B, D, and E suggest improper validation since email fields should not only accept numbers, zip codes typically do not include letters (depending on the country), and phone numbers should generally not accept letters.