casesensitive

Case sensitive refers to the property of text processing in which uppercase and lowercase letters are treated as distinct. In a case-sensitive system, the strings "Case" and "case" are different; in a case-insensitive system, they are treated as the same. Case sensitivity affects comparisons, searches, sorting, and naming in software, databases, and file systems.

In programming, many languages perform string comparisons in a case-sensitive manner by default. For example, equality checks in languages like Python, Java, or C require exact case matching unless an explicit case-insensitive approach is used, such as converting both operands to the same case or using locale-aware comparisons. Handling case correctly is important for user input, identifiers, and configuration data. Locale and Unicode considerations add complexity: case mappings are locale-dependent, and algorithms like case folding are used to compare text in a way that is more consistent across languages, albeit sometimes at the cost of precision for certain scripts. Turkish dotted and dotless I is a well-known edge case in case mapping.

File systems and databases illustrate practical differences: Linux and many UNIX systems are typically case-sensitive for file names, while Windows is usually case-insensitive but case-preserving. Databases can enforce case sensitivity or insensitivity through collation settings, affecting how string comparisons, uniqueness, and searches behave.

Practical considerations include user expectation, security, and correctness. Passwords are generally treated as case-sensitive, making exact character matching important. Developers should document behavior, apply appropriate normalization, and consider locale-specific rules when necessary.