Page 17 - Computer Class 07

In order to execute the instructions or programs written in third generation language,

the source program is to be translated to the binary form. This is done by a compiler
or interpreter. The compiler is also used to translate source program to object
program and the interpreter is also used for translation but it translates the program

line by line.
For example, (language uses a compiler to translate the programs written in C

language to machine understandable language. To execute the source program, it is
also necessary to create an executable program to execute those instructions by
linking the input and output devices in the program.

The program which performs this job done is called linker . The linker links the input-
output devices and generates an executable program from an object program.

Fourth Generation Languages or 4GLs
Fourth generation languages require fewer instruction to accomplish a particular task

than in a 3GL. Thus, programs can be written faster in a 4GL. But unlike 3GLs, 4GLS
are non-procedural languages. This means programmers need not to specify steps to
be performed for a particular task, rather they have to only specify what task is to be

performed.
Let us take an example.

Suppose that a programmer needs to display some data on a screen like address of a
student (Anubhav) from the students file.
In a 3GLs the programmer would write the following steps.

Step 1 : Get a record from the students file.
Step 2 : If this is the record for Anubhav, display the address.

Step 3 : If this is not the record for Anubhav, go to Step 1.

However, in a 4GLs, a programmer needs to write a single instruction as:
Get the address of Anubhav from students file.
4GLs are majorly used to get information from files and databases and to display or

print the information. These have a query language to answer queries with data from
a database. 4GLs, are most machine independent and are used for office automation

or business application. They are designed to be easily learnt and used by users.
Fifth Generation Languages or 5GLs

The fifth generation programming language or visual programming language, is also
known as natural language . Provides a visual or graphical interface, called a visual

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