Explain advantages and disadvantages of compilers and interpreters

Types of Programming Languages – Compilers, Interpreters and IDEs

1. Language levels – high‑level vs. low‑level

• Low‑level languages – closest to the hardware.
  • Machine code – the only low‑level language that the Cambridge IGCSE syllabus expects you to recognise. It consists of binary instructions that the CPU executes directly (e.g. 10110000 01100001).
  • Assembly language – a mnemonic representation of machine instructions (e.g. MOV AX,5). It is *not* examined in the exam, but understanding its purpose helps you see why assemblers exist.
  • Both require a translator (an assembler) to turn the human‑readable mnemonics into machine code.
• High‑level languages – hide hardware details and use English‑like syntax.
  • Examples used in the IGCSE: Python, Visual Basic, Java.
  • They are translated to machine instructions by a translator – either a compiler, an interpreter, or a hybrid (e.g. Java byte‑code + JIT).

2. Assembly language & the assembler (conceptual only)

The syllabus mentions assembly language to illustrate how low‑level code is written, but you will never be asked to write assembly yourself. The key points to remember are:

• Each assembly mnemonic corresponds to a single machine‑code instruction.
• An assembler replaces the mnemonics with the correct binary op‑codes, resolves addresses, and processes directives such as .data and .text.
• It is a *conceptual tool* for the syllabus – its inner workings are not examined.

Example (illustrative only):

        ; add 5 and 3
        MOV AX,5      ; load 5 into register AX
        ADD AX,3      ; add 3
        INT 20h       ; terminate program

The assembler would output the binary bytes that the CPU can execute directly.

3. Translators – compilers, interpreters and assemblers

4. Comparison of compilers and interpreters

5. Advantages and disadvantages

5.1 Compilers

• Advantages
  • High execution speed – code runs as native machine instructions (or fast JIT‑compiled byte‑code).
  • Early detection of many errors (syntax, type, some logic) before the program runs.
  • Opportunities for optimisation (loop unrolling, dead‑code removal, in‑lining, etc.).
  • The final executable can be distributed without revealing the source code.
• Disadvantages
  • Longer edit‑compile‑run cycle; a full recompilation is needed after each change.
  • Platform dependence – separate executables are required for Windows, macOS, Linux, etc.
  • More complex tool‑chain (compiler, linker, build scripts, sometimes makefiles).

5.2 Interpreters

• Advantages
  • Rapid prototyping – code can be run immediately after typing.
  • Excellent portability – the same source runs wherever a suitable interpreter is installed.
  • Dynamic features such as interactive debugging, runtime code generation, and REPL (Read‑Eval‑Print Loop) are easier.
• Disadvantages
  • Slower execution because translation happens at run‑time.
  • Some errors are only discovered when the problematic line is reached during execution.
  • The interpreter itself consumes extra memory in addition to the program’s data.

6. Integrated Development Environments (IDEs)

An IDE bundles the tools a programmer needs to write, test and manage code efficiently. The IGCSE syllabus expects you to be able to *describe* an IDE, not to demonstrate a particular product.

• Code editor – syntax highlighting, auto‑completion, indentation, and code snippets.
• Build / Run facility – one‑click compile (for compiled languages) or run (for interpreted languages).
• Debugger – set breakpoints, step through statements, watch variables, view the call stack.
• Error diagnostics
  • Compile‑time messages (syntax, type) for compiled languages.
  • Run‑time tracebacks for interpreted languages.
• Project & file management – organise multiple source files, libraries and resources.
• Optional enhancements – version‑control integration, refactoring tools, built‑in terminal.

7. When to choose which approach?

1. Performance‑critical applications (e.g. games, scientific simulations, large‑scale data processing) – favour compiled languages or hybrid models such as Java byte‑code with JIT.
2. Rapid prototyping, scripting or cross‑platform utilities – interpreted languages are usually more suitable.
3. Hybrid solutions – languages like Java and C# compile to an intermediate byte‑code that is later JIT‑compiled, offering a balance of speed and portability.

8. Link to the IGCSE assessment (Topic 4.2)

In the 15‑mark scenario question candidates may be asked to:

• Describe the role of an IDE.
• Compare the advantages and disadvantages of a compiler versus an interpreter for a given problem.

The exam permits only Python, Visual Basic or Java for any programming‑based task, so the tables above highlight these three languages and show how they fit the compiled‑to‑byte‑code (Java) and interpreted (Python, Visual Basic) categories.

9. Key takeaway

Compilers, interpreters and assemblers are translators that bridge human‑readable code and machine instructions. Their trade‑offs are clear:

• Compilers give speed and early error checking but need a separate build step and produce platform‑specific binaries.
• Interpreters give flexibility, portability and a fast development cycle, at the cost of slower run‑time performance.
• An IDE ties the whole development process together, providing editing, building, debugging and error‑reporting facilities.

Understanding these differences enables you to answer IGCSE questions confidently and to select the most appropriate tool for any programming problem.