Top 10 Questions for Compiler Interview

1. What are the different phases of compilation?

The different phases of compilation are:

• Lexical analysis
• Syntax analysis
• Semantic analysis
• Code generation
• Optimization

2. What is the difference between a compiler and an interpreter?

Compiler

• A compiler translates the entire source code into machine code at once.
• The compiler checks the entire source code for errors before generating machine code.
• The compiler generates a standalone executable file that can be run on any computer with the appropriate operating system.

Interpreter

• An interpreter executes the source code line by line.
• The interpreter checks each line of source code for errors as it is executed.
• The interpreter does not generate a standalone executable file.

3. What are the advantages of using a compiler over an interpreter?

The advantages of using a compiler over an interpreter include:

• Speed: Compiled code is typically much faster than interpreted code.
• Efficiency: Compiled code is more efficient than interpreted code because it does not need to be checked for errors at runtime.
• Portability: Compiled code can be run on any computer with the appropriate operating system, while interpreted code can only be run on the computer that has the interpreter installed.

4. What are the disadvantages of using a compiler over an interpreter?

The disadvantages of using a compiler over an interpreter include:

• Compilation time: Compilers can take a long time to compile large source code files.
• Debugging: It can be more difficult to debug compiled code than interpreted code because the compiler has already translated the source code into machine code.
• Error messages: Compiler error messages can be difficult to understand.

5. What are the different types of compilers?

The different types of compilers include:

• Single-pass compilers
• Multi-pass compilers
• Just-in-time (JIT) compilers

6. What is the difference between a top-down parser and a bottom-up parser?

Top-down parser

• A top-down parser starts at the root of the parse tree and works its way down.
• The top-down parser predicts the next input symbol based on the current state of the parse tree.
• The top-down parser is more efficient than the bottom-up parser.

Bottom-up parser

• A bottom-up parser starts at the leaves of the parse tree and works its way up.
• The bottom-up parser shifts the input symbols onto a stack and reduces the stack when it finds a rule that matches the symbols on the stack.
• The bottom-up parser is less efficient than the top-down parser.

7. What is the difference between a lexical analyzer and a syntax analyzer?

Lexical analyzer

• A lexical analyzer breaks the input stream into tokens.
• The lexical analyzer is responsible for identifying keywords, identifiers, operators, and other tokens.
• The lexical analyzer is the first phase of the compiler.

Syntax analyzer

• A syntax analyzer checks the sequence of tokens for grammatical errors.
• The syntax analyzer is responsible for verifying that the source code conforms to the grammar of the programming language.
• The syntax analyzer is the second phase of the compiler.

8. What is the role of the semantic analyzer in a compiler?

The semantic analyzer checks the source code for semantic errors.

• The semantic analyzer verifies that the types of the operands in an expression are compatible.
• The semantic analyzer checks for undefined variables and functions.
• The semantic analyzer is the third phase of the compiler.

9. What is the difference between a symbol table and a hash table?

Symbol table

• A symbol table is a data structure that stores the names and attributes of identifiers.
• The symbol table is used by the compiler to keep track of the scope of identifiers.
• The symbol table is implemented using a hash table.

Hash table

• A hash table is a data structure that stores key-value pairs.
• The hash table is used by the compiler to implement the symbol table.
• The hash table is a fast and efficient way to store and retrieve data.

10. What are the different optimization techniques that can be used by a compiler?

The different optimization techniques that can be used by a compiler include:

• Constant propagation
• Copy propagation
• Dead code elimination
• Loop optimization
• Register allocation