A Level Computer Science OCR Practice Exam

How does a compiler ensure efficient execution during code translation?

1. By generating executable files

2. Through building a symbol table based on the source code

3. By translating code line-by-line

4. By using just-in-time compilation

The correct answer is: Through building a symbol table based on the source code

The correct choice involves how a compiler creates a symbol table, which plays a fundamental role in ensuring efficient execution of the program after code translation. When a compiler processes the source code, it constructs a symbol table that maintains information about identifiers such as variable names, function names, and their associated types and locations. This table facilitates quick access to the identifiers during the compilation process and helps in optimizing the generated code. By having structured information about the variables and their usage, the compiler can make decisions that enhance execution efficiency, such as memory allocation, scope resolution, and error detection. The other methods mentioned, while relevant to the overall compilation process, do not directly relate to how a compiler specifically ensures efficient execution. Generating executable files is a standard output of the compilation process but does not inherently relate to the execution efficiency of the program. Translating code line-by-line is often a characteristic of interpreters rather than compilers, which typically translate whole blocks of code at once or employ optimization strategies. Just-in-time compilation is a hybrid approach that occurs at runtime, adding a layer of dynamic optimization but differing from the initial compilation process.