Question

Does alphanumeric include special characters

Answer 1

The word “alphanumeric” (or sometimes “alphameric”) usually means only the basic Latin letters A to Z and a to z plus the common digits 0 to 9, but may include a few other characters as well. The additional characters are typically other characters allowed in identifiers in some context (such as a programming language). For example, in Perl and in JavaScript, \w matches any alphanumeric character, with the underline (underscore, low line) “_” counted as a letter.

The page linked to in the question says: “In some usages, the alphanumeric character set may include both upper and lower case letters, punctuation marks, and symbols (such as @, &, and *, for example). For languages other than English, alphanumeric characters include letter variations such as é and ç.” This is all up to your definitions and conventions; “alphanumeric” means what people make it mean. But such broad (and varying) definitions are not normal in information technology.

Thus, “alphanumeric” should be expected to corresponding to what [A-Za-z0-9]matches (in common regexp syntax), unless stated otherwise or inferrable from the context.