searchandreplace

Search and replace is a text processing operation that scans input data to locate occurrences of a specified pattern and substitutes them with a replacement string. It is widely used in editors, programming languages, and data-cleaning tools to modify text efficiently.

Patterns may be literal strings or patterns defined by regular expressions. Replacement strings can include references to captured portions of the match, enabling dynamic edits. Options commonly include global replacement (all matches) versus replacing only the first or a single match, and case sensitivity or insensitivity, as well as word-boundary constraints to avoid partial matches.

Implementation typically involves a linear scan of the input, either building a new output or performing an in-place update when possible. For literal replacements, performance is often linear in input size, while regex-based replacements depend on the engine and can vary in complexity. Some engines support escaping and backreferences in the replacement text, and some support callbacks.

Applications include text normalization, code migrations, template processing, data anonymization, and localization tasks. The operation is foundational in many scripting languages and text editors, with common tools such as sed, awk, Perl, Python, and JavaScript providing built-in support.

Related concepts include string matching, pattern matching, and text editing paradigms. Cautions include the risk of unintended replacements and maintenance of context when using complex patterns.