I am writing in response to the blog post at https://www.guru99.com/difference-compiler-vs-interpreter.html titled “Compiler vs Interpreter: Complete Difference Between Compiler and Interpreter”. A compiled language is a language that requires a compiler to convert it into another language or format, like bytecode or native machine code. An interpreter translates the program to machine code as the program is running.
The blog post describes a compiler as a program that translates code into executable machine code before it is run, and an interpreter as a program that translates each statement into machine code when it is run. I think that this description is somewhat of an over-simplification. For C, compiling a C program means translating it into an executable program, which is comprised of machine code that is native to the platform it was compiled for. Compilation in general does not always refer to this particular process, though. A compiler may exist to compile one language into a different language, or even into the same language. The key is that the resulting compiled program is semantically equivalent to the original source code. If an interpreter existed for both programs then the result of interpreting the original program should be the same as the result of interpreting the compiled program.
Another detail that was not addressed by the blog post is the concept of “just in time” compilation. C programs are compiled “ahead of time”, where the code is compiled into another program before it is run. Instead of doing this, just in time compiling occurs in run time and compiles blocks of code as the program is running. This allows for a different perspective for an optimizing compiler to make the program run faster in instances that would not be possible for an ahead of time optimizing compiler that does not run in run time. Java is one such language that uses just in time compiling. The blog post does mention one detail about Java, and that is that it is both compiled and interpreted. Java is compiled into bytecode, which is portable because it is not specific to one platform’s native architecture, and then that gets interpreted into native machine code by the JVM when it is run.
From the blog CS@Worcester – klapointe blog by klapointe2 and used with permission of the author. All other rights reserved by the author.