Legacy Code Migration from Procedural to Object-Oriented Architecture

Abstract

Legacy code migration from procedural to object-oriented architecture is important for improving maintainability, scalability, modularity, and long-term software adaptability. Procedural legacy systems often contain large functions, global variables, duplicated logic, tightly connected routines, and limited abstraction, which makes modification and testing difficult over time. Traditional maintenance of procedural code may solve immediate defects, but it does not fully address deeper architectural problems such as weak encapsulation, poor reuse, and complex dependency flow. This article focuses on legacy code migration from procedural to object-oriented architecture by examining code analysis, function decomposition, class identification, data encapsulation, interface redesign, and incremental refactoring. The study discusses how procedural modules can be transformed into object-oriented components while preserving existing business logic and reducing migration risk. The article concludes that structured migration can improve code readability, reduce maintenance effort, support software reuse, and extend the useful life of legacy applications.