# **> Computer programs and programming**

Computer program: A computer program is a series of instructions given to the computer, through which almost all the problems of real life can be solved by using computer hardware and software. Hardware is the various parts of a computer like a monitor, keyboard etc. On the other hand, a program is a software. All programs that perform various user tasks like calculations, word processing, and playing games are called application software. And the programs through which the computer manages itself are called system software. Like- as Windows, Linux, Unix, Xenix etc.

Computer Programming: The main purpose of using computers is to solve problems. One of the ways to solve problems in programming. In the general sense, the process of systematically solving problems using computers is called programming. Complex problems can be solved quickly and easily through programming. In computer terms, programming is the technique of arranging instructions (Command/Statement) in order of execution for the purpose of easily solving a problem.

Programming languages and types of programming languages:

Programming Language: In daily life, we ​​use different languages ​​to communicate with each other or to solve different problems. These languages ​​are called human languages. For example, Bengali, English, Arabic, Hindi, Urdu, Persian, Greek, Latin etc. can be mentioned. Similarly, to solve problems using computers, it is necessary to establish communication between people and computers; Through which people can give various instructions to the computer. And different types of languages ​​are used to solve various problems by establishing communication between humans and computers. These languages ​​are basically programming languages.

For the purpose of solving a problem using a computer, programs or software are written using languages, those languages ​​are called programming languages ​​or programming languages. Such as Fortran, COBOL, BASIC, C, C++, C#, Java, Oracle, Pascal etc.

Types of programming languages: Types of programming languages ​​are as follows:

Programming language :

  1. Low-level language
                   Machine language
                  Assembly language
  2. High-level language

Low-level language: Low-level language or low-level language refers to machine language and assembly language.

Machine language: The language in which programs are written by arranging instructions using binary numbers (0,1) to solve problems, so machine language (Machine language).

    (i) A program written in machine language is called an object program.

    (ii) Writing programs in this language is relatively difficult and time-consuming. No translator program is 
          required to execute the program written in this language.

    (iii) Programs written for one type of machine cannot be used on another type of machine.

    (iv) It is essential to have a clear understanding of each instruction and memory address in the 
           computer to write programs in this language.

Assembly language: The language in which the program is written using special abbreviations or mnemonics (ADD, SUB MUL, DIV, LOAD MOV, MVI. JMP, JNZ, INC etc.) is called assembly language. Like- MASM, TASM etc.

      (i) A program written in this language is called a source program.

       (ii) While writing programs in assembly language is easier and less time-consuming than in machine 
              language, it is more difficult and time-consuming than in high-level languages.

      (iii) A lot of commands have to be memorized for writing programs in this language.

      (iv) To execute the program written in this language translator program (assembler) is required.

High-level language: An easy-to-understand universal language for writing programs in which many words of the normal language (English) are used, is called a high-level language (High-level language). Like- Visual, C++, Java, Oracle, Pascal, Visual Basic etc.

              (i) Disadvantages of machine language and assembly language have been overcome in this       
                   language. Hence modification, enhancement, editing and maintenance of programs written in 
                    this language are easy and less time-consuming.

              (ii) A program written in this language is also called a source program.

              (iii) No knowledge of computer internal organization is required to write programs in this 
                     language. That is, this program is not machine dependent.

              (iv) Translator programs (compilers and interpreters) are required to execute programs written in 
                    this language.

              (v) It is difficult to understand programs and understand various instructions or statements in this 
                    language

              (v) It has the advantage of numerous built-in>  library functions.

Different types of high-level programming language: It is not possible to solve all types of problems through only one high-level language. A high-level language is particularly useful for solving one type of problem. Due to these reasons, various types of high-level languages ​​have arisen.

Fortran: In 1957, Dr IBM Company. Fortran was developed by James Backer. Its full name is Formula Translation, commonly used in scientific and engineering work that requires Fortran to use a variety of mathematical formulas.

Cobol: The full name is Common Business Oriented Language, COBOL was developed in 1960 to develop business software.

BASIC: Not only for specific tasks but also using programming language to solve any problem and to teach students easily, BASIC (Beginners All-purpose Symbolic Instruction Code) language was developed for this purpose. It was first used in 1960 at Dartmouth College in the United States.

Pascal: In the late 1970s, Professor Niklas Huirth of Switzerland developed Pascal to teach programming easily and smoothly. Pascal is the first modular programming language. In modular programming language, it means that every big program can be divided into several sub-programs and each sub-program works separately. Pascal is not an abbreviation of a full name like the names of other programming languages. But since Pascal is the first modular language, it is natural to have some limitations. Besides, Pascal is not so widely used in scientific, mathematical and business work.

C: To make the program more dynamic and use the programming language to easily /O device. memory or other devices can be controlled, CC is not developed to solve any particular problem. It is developed to solve any problem (be it scientific or mathematical or business). Compared to other programming languages, C is very rich in terms of library functions. However, apart from the above-mentioned programming languages, some other languages ​​have been developed at different times and places for application in specific fields. Like- PROLOG, APL, PL/1, Ada, LISP, LOGO, PILOT, Perl, CSL etc.