3.6 HIGH
LEVEL LANGUAGES
You know
that assembly language and machine level language require deep knowledge of
computer hardware where as in higher language you have to know only the
instructions in English words and logic of the problem irrespective of the type
of computer you are using.
Higher
level languages are simple languages that use English and mathematical symbols
like +, -, %, / etc. for its program construction.
You should
know that any higher level language has to be converted to machine language for
the computer to understand.
Higher
level languages are problem-oriented languages because the instructions are
suitable for solving a particular problem. For example COBOL (Common Business
Oriented Language) is mostly suitable for business oriented language where
there is very little processing and huge output. There are mathematical
oriented languages like FORTRAN (Formula Translation) and BASIC (Beginners
All-purpose Symbolic Instruction Code) where very large processing is required.
Thus a
problem oriented language designed in such a way that its instruction may be
written more like the language of the problem. For example, businessmen use
business term and scientists use scientific terms in their respective
languages.
Advantages of High Level Languages
Higher
level languages have a major advantage over machine and assembly languages that
higher level languages are easy to learn and use. It is because that they are
similar to the languages used by us in our day to day life.
3.6.1 Compiler
It is a
program translator that translates the instruction of a higher level language
to machine language. It is called compiler because it compiles machine language
instructions for every program instructions of higher level language. Thus
compiler is a program translator like assembler but more sophisticated. It
scans the entire program first and then translates it into machine code.
The
programs written by the programmer in higher level language is called source program. After this program is
converted to machine languages by the compiler it is called object program.
Higher Level Language
---------------------------------- ® (Compile) ® Program Machine
Language Program
Fig. 3.2
A compiler
can translate only those source programs, which have been written, in that
language for which the compiler is meant for.
For example FORTRAN compiler will not compile source code written in
COBOL language.
Object
program generated by compiler is machine dependent. It means programs compiled
for one type of machine will not run in another type. Therefore every type of
machine must have its personal compiler for a particular language. Machine
independence is achieved by using one higher level language in different
machines.
3.6.2 Interpreter
An
interpreter is another type of program translator used for translating higher
level language into machine language. It takes one statement of higher level
languages, translate it into machine language and immediately execute it.
Translation and execution are carried out for each statement. It differs from
compiler, which translate the entire source program into machine code and does
involve in its execution.
.
The
advantage of interpreter compared to compiler is its fast response to changes
in source program. It eliminates the need for a separate compilation after
changes to each program. Interpreters are easy to write and do not require
large memory in computer. The disadvantage of interpreter is that it is time
consuming method because each time a statement in a program is executed then it
is first translated. Thus compiled machine language program runs much faster
than an interpreted program.
IN-TEXT QUESTIONS 3
1. What is the difference between interpreter and
compiler?
2. Give some examples of high level language.
3.
Write True or False
(a)
High level languages are problem-oriented language.
(b)
Object program generated by compiler is machine independent.
(c) The disadvantage of interpreter
is that it is time consuming.
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