Data validation rules can be defined and designed using any of various methodologies, and be deployed in any of various contexts.
In evaluating the basics of data validation, generalizations can be made regarding the different types of validation, according to the scope, complexity, and purpose of the various validation operations to be carried out.
For example: Data type validation is customarily carried out on one or more simple data fields.
Others use the term in a more narrow context to simply mean "checking if an input conforms to expectations without changing it." If a programmer believes that an attacker cannot modify certain inputs, then the programmer might not perform any input validation at all.
For example, in web applications, many programmers believe that cookies and hidden form fields can not be modified from a web browser (CWE-472), although they can be altered using a proxy or a custom program.
start date is before end date, price is within expected range).
It is always recommended to prevent attacks as early as possible in the processing of the user’s (attacker's) request.
The first ("%d") specifies what type of data type is expected (ie char, int, or float). The second argument (&number) specifies the variable into which the typed response will be placed.
In this case the response will be placed into the memory location associated with the variable number.
Syntactic validation should enforce correct syntax of structured fields (e.g.