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Interpreter:

An interpreter works by reading a statement of the source code and immediately performing the required action.

>it may do this by interpreter the syntax of each statement, or by calling predefined routines. In some cases, the source code is translated into an intermediate format before it is executed.

Interpreters may examine every statement, which may reduce efficiency.

Benefits of using an interpreter:

>you do not need to compile the whole program, in order to run sections of code; you can execute the code, one statement at a time.

>as the code is translated each time it is executed, program code can be run on processors with different instruction sets.

>because of this, an interpreter is most likely to be used whilst a program is being developed.

Downsides of using an interpreter:

>no matter how many times a section is revisited in a program it will need translating each time, this means the overall time needed to execute a program can be very long.

>the source code can only be translated and therefore executed on a computer that has the same interpreter installed.

>the source code must be distributed to users, whereas with a compiled program, only executable code is needed.

Compiler:

A compiler coverts the whole source code into object code before the program can be executed.

>the good thing about this is that once you have carried out this process you will have some object code that can be executed immediately every time, so the execution time will be quick.

>this is ideal, once you have sorted out all the bugs in your program.

Benefits of using a compiler:

>once the source code has been compiled you no longer need the compiler, or the source code.

>if you want to pass your object code, on to someone else to use they will find it difficult to work out what the original source was code, this is the process of working out what the source code was is known as reverse engineering.

Downsides of using a compiler:

>because the whole program has to be converted from source code to object code every time you make even the slightest alteration to your code, it can take a long time to debug.

>the object code will only run on a computer that has the same platform.