identifiersstrings

Identifier strings are sequences of characters used to name entities in software systems, such as variables, functions, tables, columns, or resources. They function as labels rather than data values and are interpreted by language runtimes, compilers, and databases to locate or reference the corresponding entity.

Rules for forming identifier strings vary by language and system, but most programming languages require an initial character from a letter or underscore, with subsequent characters drawn from letters, digits, and sometimes underscores or other allowed symbols. Many languages are case sensitive, and a number of reserved words or keywords cannot be used as identifiers. Some environments support Unicode identifiers, enabling characters beyond ASCII, while others restrict to ASCII.

In databases and other queryable systems, identifiers may need to be quoted or delimited to include spaces or punctuation, and there are often length limits. The exact quoting syntax and the set of valid characters depend on the database system (for example, delimited identifiers or quoted identifiers in SQL variants).

Best practices include choosing descriptive, consistent names, avoiding reserved words, following the conventions of the target language, and documenting any special rules for escaping or quoting. Common pitfalls include relying on case-insensitivity, using ambiguous abbreviations, and selecting identifiers that collide with system-reserved names.

Example identifier strings include variable_name in many languages, user_id, OrderTotal in Java or C-like languages, and columnName in SQL when quoted appropriately. The treatment of identifiers thus reflects the specific syntax and semantics of the used programming or data-management environment.