StringtoUpperCase

StringtoUpperCase is a function or method used in many programming languages to convert all applicable characters in a string to their uppercase equivalents. The operation typically affects alphabetic characters by mapping each character to its Unicode uppercase form, while non-letter characters such as digits and punctuation are left unchanged.

Most implementations are Unicode-aware, performing the mapping based on the Unicode code points. Some languages also provide a locale-sensitive variant that can change certain mappings depending on language rules. For example, Turkish and Azeri languages treat the letter i differently in uppercase. In practice, toLocaleUpperCase or equivalent functions take a locale parameter or use the runtime’s current locale to influence the result.

Function naming varies across languages. Some environments expose a method named toUpperCase (for example in JavaScript and Java), or strtoupper (in PHP), or StringtoUpperCase in other libraries. The concept is the same: produce a new string or modify in place, depending on the language. In-place modification is less common for immutable string types.

Performance is typically linear in the length of the input string, with memory proportional to the output length. Edge cases include characters represented by surrogate pairs or combining marks, which may require careful handling to produce a visually correct result in all scripts. Some characters may map to multiple code points in certain contexts.

See also: toUpperCase, toLocaleUpperCase, uppercase, locale, Unicode case mappings.