1. Interpreter Vs Compiler
By : Aya Yakout Alkhamese
Compiler
4th
Dept : Computer Science & Information Technology
Faculty of Science – Portsaid Univeristy

2. • Interpreter Vs Compiler
 Programming languages can be divided into two major categories: low level and
high level. “Assembly language” and “machine language” are called low-level
languages because they more than others “speak” the language the computer
understands. On the other hand, C, C++, Pascal,Python, Visual Basic, Java,
and COBOL are high-level languages because they require more manipulation by
the computer, a process called compiling.
 When writing programs in a high level language, the computer will not be able
to understand it. So that it will be usable, you need to convert it into
something that a computer understands. This is where compilers and
interpreters come in as they both do the same function – convert a high level
language (like C, Java) instructions into the binary form which is
understandable by computer hardware. They are the software used to execute
the high level programs and codes to perform various tasks. Specific
compilers/interpreters are designed for different high level languages.
However both compiler and interpreter have the same objective but they
differ in the way they accomplish their task
 An interpreter :
 reads the source code one instruction or line at a time, converts this line into
machine code and executes it. The machine code is then discarded and the next line
is read. executing each line as it is "translated," much the way a foreign language
interpreter would translate a book, by translating one line at a time.
 The interpreter takes one statement then translates it and executes it and then
takes another statement.
 interpreter stops translating after the first error.
 Programming Steps for Interpretion :
• Edit the Program
• No linking
• No object code generated
• Source statements executed line by line

3.  The advantage of this is that :
• Interpreters however are easier to use, particularly for
beginners, since errors are immediately displayed, corrected
by the user, until the program is able to be executed.
• you can interrupt it while it is running, change
the program and either continue or start again.
 The disadvantage of this is that :
• every line has to be translated every time it is executed,
even if it is executed many times as the program runs.
Because of this interpreters tend to be slow. that
interpreted programs run much slower than compiled
programs. As much as 5-10 times slower as every line of
code has to be re-read, then re-processed.
• interpreted programs can only run on computers that also
have the interpreter.
 Examples of interpreters are Basic on older home computers, and script
interpreters such as JavaScript, and languages such as Lisp and Forth.
A compiler :
 reads the whole program (called source code) written in some high level language
and translates code of a programming language in machine code "binarycode,", also
called object code. The object code can be executed directly on the machine where
it was compiled.
 a special program that analyses all the statements in a program (called source
code) written in some high level language and links the code (using libraries) to
produce an executable. To run the program you submit the executable which would
produce some output. To make changes in the program you must repeat these
steps .

4.  the compiler translates the entire program in one go and then executes it.
 Compilers, on the other hand, analyse the entire program, taking note of where
errors have occurred, and places these in an error/diagnostic file. If errors have
occurred then the program cannot run. Programmers must then use the error
messages to identify and remove the errors in the source code. Some compilers
assist by adding line numbers to the source listing to help pinpoint errors .
compilers offer programmers some advantages. compiled programs make the
programmer wait until the program is complete.
Programming Steps for Compilation :
 Edit the Program
 parses or analyzes all of the language statements syntactically in a sequential
manner and then, in one or more successive passes, builds the output code, ensuring
that statements that refer to other statements are referenced correctly in the
final code.
 Link the Machine code files into a runnable program (also known as an exe).
 Debug or Run the Program
 The advantage of this is that :
• the translation is done once only and as a separate process.
The program that is run is already translated into machine
code so is much faster in execution.
• compiled programs can run on any computer
 The disadvantage of this is that :
• you cannot change the program without going back to the
original source code, editing that and recompiling (though
for a professional software developer this is more of an
advantage because it stops source code being copied, so
there’s an element of security built in to compiled
programs.).
 Examples of compilers are Visual Basic, C, C++, C#, Fortran, Cobol, Ada, Pascal and
so on.
 A compiler works with what are sometimes called 3GL and higher-level languages
(3rd-generation languages, such as Java and C