Section 16.3
High Level Programming
16.3 Language Generations
Each successive gerneration of computer language represents a significant
development.
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1st Generation (late 1940s)
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Machine code
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2nd Generation (late 1950 - late 1970s)
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Unstructured Procedural Langauges (E.g. FORTRAN)
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3rd Generation (late 1970s - mid 1980s)
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Structured Procedural Languages
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4th Generation (mid 1980s...)
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Database Integration & Object Oriented Programming
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5th Generation (1980s...)
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Declaritive Languages (E.g. Prolog & AI)
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16.3.1 Fourth Generation Languages
In the 4GL the programmer sometimes specifies what is to be done, rather than
how to do it.
A 4GL is an integrated development environment. Typically this provides:
- DBMS (Database Management System)
- Data Dictionary
- Query Language (SQL)
- Facilities for selection and sorting
- Report Generation
- Screen Painting
- Text Editor
- Security And Password Facilities
- Backup And Recovery Facilities
- Links to other DBMSs
It is the close integration of the DBMS with a programming language that leads
to it being classified as a 4GL.
16.3.2 Advantages Of 4GLs
- Prototyping is readily acheived. Either through:
- Throw away prototyping OR
- Evolutionary prototyping
- Programs productivity is increased
- Program maintanence is easier
- 4GLS are more portable than 5GLS
