Introduction to programming languages

This is obsolete content Click Here to View Updated Version and Much more

Program

A well-defined set of instructions given to the computer is called program. A person who develops program is called programmer.The program has an executable form that the computer can use directly to execute the instructions. The same program in its human-readable source code form, enables a programmer to study and develop the algorithm. Because the instructions can be carried out in different types of computers, a single set of source instructions converts to machine instructions according to the central processing unit type.

Programming language

A set of words and symbols used to write programs is called programming language. A programming language is a mean of communication between a user and computer.

Types of programming languages

Ther are two Types of programming languages:
  1. Low level language
  2. High level language

Low level language

Low level languages are near to computer hardware and far from human languages.
There are two types of low level languages:

Machine language

In machine language instructions are written in binary form as 0 or 1. This is the only language that is directly understood by computer.

Assembly language

In assembly language machine instructions are replaced with English like words. It is one step higher than machine language.

High level language

A type of language that close to human languages are called high level language. The instructions in these languages are similar to English language such as printf and input etc. these languages are easy to understand. Every high level language defines a set of rules for writing programs called syntax. Each instruction must be written according to the syntax of the language.

Object code

A program in machine language is called object code. It is also called object program or machine code.

Source code

A program written in a high level language is called source code. Source code also called source program.it must be converted into object code before execution.

Compiler

Compiler is a program that convers the instructions of high level language into machine language as a whole. The compiler checks each statement in the source program and generates machine instructions. Compiler also checks syntax error in source program. A source program containing any error cannot be compiled.