Translate the source code of the whole program at a time
Producing object code stored in hard disk
Object code
[in hard disk] ↓
Linker
↓
The Linker links the object files and libraries together to form an executable file
Executable code
[in hard disk] ↓
Loader
↓
What is the function of loader?
Loader is used to load the executable file into the main memory
Features of loader:
Loader is a part of the operating system
It is loaded when the computer is booted and it resides in memory
Executable code
[in main memory]
Translators
What is the function of translator?
Translators are used to convert source codes into object codes.
Only the code format will be changed, the purpose and function will not be affected.
There are three types of translators:
Assemblers: it is used to translate assembly language to machine language. (i.e., it is designed for low level language)
Interpreters / Compilers: They are used by high level languages, such as C++ and Python etc.
Interpreters[DSE 2018 P2D Q2(e)]
It is not necessary to compile the source code in advance
An interpreter will translate a source code into immediate instruction / efficient intermediate representation and immediately execute it
If there is any syntax error during the execution → the program may stop executing (e.g., Python)
Compliers
Translates the source code of the whole program to object code at a time
Interpreters and Compilers
What are the differences between an interpreter and a compiler?
Interpreter
Compiler
Mode of translation
Translates program one statement at a time → Translating a source code into immediate instructions and immediately executing it → Not necessary to compile the source code in advance
Scans the entire program and translates it as a whole into machine codes → Translation can be done once only (especially for some iterations)
Execution time
Interpreters usually take less time to analyze the source code
However, the execution code is less optimized → The overall execution time is comparatively slower than compilers
Compilers usually take more time to analyze the source code
However, the execution code can be optimized better during compilation stage → The execution time of the program is shorter
Storage space
No object code is generated → more memory efficient (need more storage space)
More memory efficient (save storage space) as no intermediate object code is generated
Convenient for programmers to test and debug during the development of the program [As interpreters execute codes line-by-line, programmers can modify and test their code in real-time, without having to recompile the whole program]
No translation is needed during the execution of the program
Compiled code runs faster / execution time is shorter
Optimization can be done during the compilation stage
