PGCB Sub-Assistant Engineer (CSE) Exam: 30.09.2021 (BUET)প্রশ্ন ও সমাধান

Compiler vs Interpreter

Aspect	Compiler	Interpreter
Translation	Translates the entire source program into machine code before execution	Translates and executes source code line by line
Output	Produces a standalone executable file	No separate executable; needs the interpreter present every run
Speed of execution	Faster (translation done once, ahead of time)	Slower (translation overhead repeats every run)
Error detection	Reports all syntax errors after scanning the whole program	Stops at the very first error encountered
Examples	C, C++, Rust, Go	Python (bytecode-interpreted), classic BASIC, shell scripts
Debugging	Harder to debug line-by-line (must recompile after every fix)	Easier to debug interactively (test-fix-run one statement at a time)

graph LR
  S1[Source Code] --> C[Compiler] --> E[Executable Machine Code] --> R1[Run - fast, repeatable]
  S2[Source Code] --> I[Interpreter] --> R2[Execute line-by-line - slower, no separate exe]

Middle ground: many modern languages (Java, C#, Python with a JIT) use a hybrid approach - compiling to an intermediate bytecode, then interpreting or JIT-compiling that bytecode at run time, balancing portability with speed.

Exam takeaway: a compiler translates everything first, then runs fast; an interpreter translates and runs one line at a time, more flexible but slower - the trade-off is upfront translation time and portability versus per-run execution speed.