Compiler vs Interpreter

Richard Shaju
4 min readApr 5, 2024

Compilers and interpreters are both programs that translate code written in a high-level programming language into a form that the computer can understand and execute. However, they differ in how they achieve this translation:

Compiler

  • A compiler translates the entire source code written in a high-level language (like C++ or Java) into machine code, the specific language the computer’s processor understands. This machine code is typically stored in a separate file. The compilation process can take time as the compiler analyzes the entire code for errors and optimizes it for performance. Once compiled, the machine code can be executed directly without the compiler, making it faster to run.
  • Compiled code generally runs faster because the translation process optimizes the code for the target platform. Once compiled, the code execution doesn’t require re-translation.

Interpreter

  • An interpreter translates the source code line by line as the program is being executed. This means there’s no separate machine code file generated. Interpreters are often used for scripting languages like Python or JavaScript. They are faster to set up because there’s no compilation step, but the interpretation process can be slower than running compiled code.
  • Interpreted code typically runs slower because it has to be translated and executed line by line during runtime.

Let’s check the merits and demerits of both

Merits of Compilers:

  1. Performance: Compiled code tends to execute faster than interpreted code because it’s translated directly into machine code optimized for the target platform.
  2. Portability: Once compiled, the executable code can be distributed and run on machines without the need for the original source code or the compiler itself.
  3. Error Checking: Compilers often perform static analysis of the source code, catching errors like syntax errors, type errors, and other potential bugs before the program is executed.

Demerits of Compilers:

  1. Compilation Time: Compiling large programs can take significant time, especially for languages with complex syntax or extensive libraries. This can slow down the development process.
  2. Platform Dependence: Compiled code is often platform-dependent, meaning it may not run on different architectures without recompilation.
  3. Debugging: Debugging compiled code can be more challenging since the generated machine code is not directly tied to the source code. Debugging symbols are needed to map machine code back to the source.

Merits of Interpreters:

  1. Portability: Interpreted languages are usually more portable since the interpreter can run on different platforms, allowing the same source code to be executed without modification.
  2. Ease of Debugging: Interpreters typically provide better debugging support as they execute the source code directly. Developers can step through the code line by line, inspect variables, and modify the code during runtime.
  3. Rapid Development: Since there’s no separate compilation step, changes made to the source code can be immediately tested and executed, speeding up the development process.

Demerits of Interpreters:

  1. Performance Overhead: Interpreted code tends to run slower than compiled code because it’s translated and executed line by line during runtime.
  2. Dependency on Interpreter: Interpreted programs require the interpreter to be installed on the target system. This can be a limitation when distributing software to environments where the interpreter is unavailable or must be compatible.
  3. Less Optimization: Interpreters typically perform fewer optimizations compared to compilers since they don’t have the luxury of analyzing the entire program before execution.

Choosing between a compiler and an interpreter depends on the program’s specific needs. Compiled programs are generally faster and more efficient for tasks that need to run frequently. Interpreted languages are often preferred for scripting or situations where rapid development and debugging are crucial.

As mentioned in the comments,

This article's explanation lacked details about languages like Java/C# compared to C, and the role of JIT compilation. Here’s a breakdown:

Compilation Target:

  • C: C code is typically compiled directly into machine code for the specific processor it will run on. This gives C programs the potential for the fastest execution speed because the machine code can be directly executed by the CPU without any further translation.
  • Java/C#: These languages are compiled into an intermediate language (bytecode) like Java Bytecode (for JVM) or Common Intermediate Language (CIL) for CLR. This bytecode is not specific to any machine and can run on any system that has a Java Virtual Machine (JVM) or Common Language Runtime (CLR) installed. This provides platform independence but adds an extra step (interpretation or JIT compilation) before the code can be executed.

JavaScript and JIT:

  • JavaScript: Modern JavaScript engines use JIT compilation to improve performance. The JavaScript code is initially interpreted, but frequently used functions or code segments can be JIT-compiled into machine code for faster execution. This doesn’t necessarily make JavaScript as fast as Java, but it can significantly close the gap.

Performance Considerations:

  • Native Code ©: Generally offers the best potential performance due to direct machine code execution.
  • JIT-compiled languages (Java/C#/JavaScript): Can achieve very good performance due to JIT, but there’s still some overhead compared to native code.
  • Interpreted languages (Pure Python): Typically slower than compiled or JIT-compiled languages.

I hope this article helps you❤️

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Richard Shaju
Richard Shaju

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