Computer language

The language that is used to write a computer program is called computer language. They are broadly classified into two types:

1. Low level language
2. High level language

Low level language:

It is a language that is understandable by the computer. Here each programme statements is converted to single machine language statement. There are two types of low level languages.

Machine level language:

In this language the data and instruction are represented in the form of strings of 0s and 1s. Every instruction is represented in the form of binary bit pattern. For e.g., the instructions add is represented as "0110001". Similarly the instruction divide has bit pattern of "0110000".

Disadvantages of machine level language:

• It is difficult to remember the bit pattern for every instruction when the number of instructions is very large.
• if there is mistake in single bit the meaning would be totally different.

Advantages of machine level language:

• Execution of the code is faster than any other languages

Assembly language:

In this language, instead of using binary codes, short codes are used which are called "MNEMONICS". Each "MNEMONICS" has two parts, the first part is instruction and second part is data for, e.g. ADD A, B is a MNEMONICS, where ADD is instruction part and A & B are data parts. Due to use of short codes, programmers do not require remembering bit pattern which is very tedious task.

Advantages of Assembly language:

• Since "MNEMONICS" code replace machine instruction, they are easy to understand, write and debug in comparison to machine codes.
• Useful for writing lightweight application for example, code to control traffic lights.

Disadvantages:

• It is machine dependent and incompatible to other machine.
• It is very difficult to debug

High level language: (third generation language):

High level language statements are written in English-like structure. Structure written in this language is called statements or command. It is easier to learn and master this language. Either complier or interpreter is used to convent high level language statements to machine understandable form for e.g. PASCAL, C, C++, Java, QBASIC.

Advantages:

• Easy to write, debug and test the program because, high level languages are English like language.
• No need to remember loots of MNEOMIC codes or other unusual codes as in assembly language or machine language.
• Each and every statements build with some pre- define syntax, which guides the programmer about the way how the programmes should be written.
• They are machine independent.

Disadvantages:

• Since it is written in human language/English language, it is heavy weight and execution of programmes is slower.
• Every programming language must have its own translator because high level language cannot directly generate executable code.
• The conservation time of high level language to machine level language is longer than conversion from assembly level language to machine level language.

Fourth generation language:

It is an advanced form of high level language. The programme statements of fourth generation computers are more user friendly than other level of languages. It is also called 4G.L. and are designed to provide higher level abstraction, reduced programming effort and reduce cost of development. The languages are result oriented and has heavy data processing and query capability. 4G.L. needs to be translated to machine understandable form by using either interpreters or compiler for e.g. 4GL , oracle, access, MARLAB.

Advantages:

• Easy to use and implement because programming can be done without having knowledge of instruction set and syntax of instruction.
• Software developed using 4 GL are more user friendly.

Disadvantages:

• Compiler or interpreters for this language are large and heavy weight.
• Need larger time to convert to machine language than other languages.
• Programmes run slower.

Fifth generation Languages:

A fifth generation (programming) language (5GL) is a grouping of programming languages build on the premise that a problem can be solved, and an application built to solve it, by providing constraints to the program (constraint-based programming), rather than specifying algorithmic-ally how the problem is to be solved (imperative programming).

Language Translators:

Language translator does the work of conversation of high level language into machine understandable form. There are three types of language translator:

Assembler

It converts assembly language statements into machine understandable form, i.e. of Os and 1s.

Interpreter:

It converts high level language statements into binary file Os and 1 s. Conversion is done letter by letter, word by word and line by line. When every letter, word and line are correctly written, the interpreter will convent that line into file of O and 1. The conversion process is slow in comparison to compiler.

Compiler:

It converts high level language statements into machine understandable form and is done at single step unlike interpreter. A compiler checks entire user written programmes and if error free, produces the complete program in machine language. If the program use some library functions, the library functions are linked to other object program to generate executable program.

Difference between high and low level language: