A Level Computer Science OCR Practice Exam

What does the symbol table in a compiler store?

1. Executable code

2. Data about error messages

3. Keywords, constants, variables, and operators

4. The final compiled code

The correct answer is: Keywords, constants, variables, and operators

The symbol table in a compiler is crucial for the compilation process as it serves as a data structure used to store information about identifiers in the program being compiled. This information typically includes keywords, constants, variables, and operators, along with details such as their names, types, scopes, and locations in memory. By maintaining a symbol table, the compiler effectively tracks the identifiers throughout the different stages of compilation, including syntax analysis and semantic analysis. This allows for proper attribute checking and ensures that identifiers are used correctly according to their defined types and scopes. The symbol table plays a significant role in declaration, definition, and usage verification of program elements, making it essential for error checking and providing accurate information during code generation. Other options do not align with the function of the symbol table. For instance, executable code and the final compiled code refer to the end product of the compilation process rather than the intermediary information stored during compilation. Data about error messages is related to the diagnostics of the compilation process but is not the primary focus of what the symbol table manages.