Structured programming, also known as modular programming, is a programming paradigm that aims to improve the clarity, quality, and development time of a computer program by making extensive use of structured control flow constructs. It encourages dividing an application program into a hierarchy of modules or autonomous elements, which may contain other such elements. Within each element, code may be further structured using blocks of related logic designed to improve readability and maintainability. Structured programming languages facilitate or enforce structured programming practices, which date back to the emergence of structured programming languages.
Some key features of structured programming include:
- Control structures: Following the structured program theorem, all programs are seen as composed of three control structures: sequence, selection, and iteration. These structures are sufficient to express any computable function.
- Modules: Structured programs consist of a structural hierarchy starting with the main process and decomposing downward to lower levels as the logic dictates. These lower structures are the modules of the program, and modules may contain both calls to other lower-level modules and blocks representing structured condition/action combinations.
- Single-entry and single-exit: The entry and exit in a structured program is a single-time event, meaning that the program uses single-entry and single-exit elements. Therefore, a structured program is a well-maintained, neat, and clean program.
Structured programming can be done in any programming language, but it is preferable to use something like a procedural programming language. Structured programming is considered a precursor to object-oriented programming (OOP) .
