A Level Computer Science OCR Practice Exam

What is the purpose of lexical analysis in a compiler?

1. To execute the compiled code

2. To manage memory effectively

3. To prepare the code for reading and tokenizing

4. To optimize the execution time

The correct answer is: To prepare the code for reading and tokenizing

Lexical analysis is the first phase of the compilation process, where the source code is read and processed to formulate meaningful symbols known as tokens. The primary purpose of this stage is to prepare the code for subsequent phases of compilation, ensuring that the syntax of the programming language is correctly interpreted. During lexical analysis, the code is broken down into its fundamental elements, such as keywords, identifiers, operators, and literals, which helps in forming a structured representation of the input code. This tokenization is crucial because it provides a simpler representation for the parser in the next phase of compilation, ensuring that it can work with these tokens rather than the more complex raw code. This process is essential for identifying valid sequences of characters in the source code, which sets the groundwork for further syntactic and semantic analysis. The other provided options involve different aspects of the compilation and execution process. Executing the compiled code relates to the machine code generation and runtime processes, managing memory is more associated with runtime management rather than compilation phases, and optimizing execution time is usually addressed in later stages of compilation, such as optimization phases that focus on refining the generated code for better performance. Thus, the focus on preparing the code for reading and tokenizing accurately reflects the role of lexical analysis.