Validating user input
This stands to reason that all input should be checked and validated, because you do not know exactly who or what is giving you input to process.Applications and software should check all input entered by a user, but this is not the only time that input should be checked. Was it your application, was it another application, is it some shared database table that another application is storing data in that you would never expect?For example, a US phone number should have 10 digits and no letters or special characters.Code and cross-reference validation includes tests for data type validation, combined with one or more operations to verify that the user-supplied data is consistent with one or more external rules, requirements, or validity constraints relevant to a particular organization, context or set of underlying assumptions.For example: Data type validation is customarily carried out on one or more simple data fields.
Data validation rules can be defined and designed using any of various methodologies, and be deployed in any of various contexts.
A Validation rule is a criterion or constraint used in the process of data validation, carried out after the data has been encoded onto an input medium and involves a data vet or validation program.
This is distinct from formal verification, where the operation of a program is determined to be that which was intended, and that meets the purpose.
In computer science, data validation is the process of ensuring data have undergone data cleansing to ensure they have data quality, that is, that they are both correct and useful.
It uses routines, often called "validation rules" "validation constraints" or "check routines", that check for correctness, meaningfulness, and security of data that are input to the system.