This extension filters data by either validating or sanitizing it. This is especially useful when the data source contains unknown (or foreign) data, like user supplied input. For example, this data may come from an HTML form.

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There are two main types of filtering: validation and sanitization.

Validationis used to validate or check if the data meets certain qualifications. For example, passing in FILTER_VALIDATE_EMAILwill determine if the data is a valid email address, but will not change the data itself.

Sanitizationwill sanitize the data, so it may alter it by removing undesired characters. For example, passing in FILTER_SANITIZE_EMAILwill remove characters that are inappropriate for an email address to contain. That said, it does not validate the data.

Flags are optionally used with both validation and sanitization to tweak behaviour according to need. For example, passing in FILTER_FLAG_PATH_REQUIREDwhile filtering an URL will require a path (like /foo in http://example.org/foo) to be present.

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