Some documentation and references interchangeably use the various meanings, which is very confusing to all concerned.
Note that you should proceed to validate the resulting numbers as well.
As you see, this is not only beneficial for security, but it also allows you to accept and use a wider range of valid user input.
However, there are bad, good and "best" approaches.
Often the best approach is the simplest in terms of code.
There are four strategies for validating data, and they should be used in this order: This strategy is also known as "whitelist" or "positive" validation.
The idea is that you should check that the data is one of a set of tightly constrained known good values. Data should be: This strategy, also known as "negative" or "blacklist" validation is a weak alternative to positive validation.To ensure that the application is robust against all forms of input data, whether obtained from the user, infrastructure, external entities or database systems. This weakness leads to almost all of the major vulnerabilities in applications, such as Interpreter Injection, locale/Unicode attacks, file system attacks and buffer overflows. All sections should be reviewed The most common web application security weakness is the failure to properly validate input from the client or environment.Say you want to set up a site where users can upload arbitrary files so they can share them or download them again from another location.In this case validation is impossible because there is no valid or invalid content.Here are some examples: If you expect a phone number, you can strip out all non-digit characters.