Java lesson-1

Java is a programming language used to create internet applications. It was created by sun micro system and now it is in the hands of Oracle Corporation.

From its invention c, c++ was very popular. At that time variety of electronic devices were invented. To write program for electronic devices each need a different compiler. Compiler was a costly one.so they needed a portable language which has needed same code for all electronic applications.

Second reason for java invention is invention of internet. C, C++ language were created before invention of internet. So they need a new language to code web applications. So java made suitable for creating web applications.

Oak is the first name of java language. After that it was renamed as java. Java is both compiled and interpreted language. First java program is compiled and class file is created. After that it interpreted by java virtual machine (JVM)   and run.

Java is an object oriented language. And also java is a modern language. It has the modern features such as exception handling, multi-threading and garbage collection.java garbage collector automatically release the memory used by objects.

There is no pointer concept in java. So we cannot access local memory of a system where java program was running.so malpractices such as hacking is not possible by java. So java is called as secured language. Before learn java install jdk and an ide (Netbeans or eclipse) in your System.

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c language learn chapter-1

What is c? 

it is a programming language
Commonly software is split into two types. They are
1. Language
2. Package.

What is package?

Example are ms-word, excel.

Packages are already predefined .That is if we want to format a paragraph there are icons in word software such as bold and italic by just clicking these icons we can format text. That is what should happen when we click bold icon is already predefined.

what is language

Opposite to it in programming language there will be set of statements. By executing these statements we can make solution to a problem. We can make packages using languages . that is what should happen in a package when events such as clicking a bold icon are defined through programming language.

We can also write operating system using languages like c.

What is an operating system?

Operating system is also software. It comes in the type of system software. This soft ware manages the system . i.e allocating memory to an application or setting priorities to software such as which should run first. It is also act as a interface between system and user. 

Examples for operating system are

1. Windows xp
2. Windows 7
3. Unix
4. Linux

In 1972 at bell laboratories, USA a research of developing UNIX operating system was going on. To write UNIX operating system they needed a language. So they were in the need of a programming language. So they developed c language. So the reason behind invention of c is to write UNIX operating system.

C is a portable language.

Why it is called as portable language?

A program written in c language in one platform can be run on another platform without change. So c is called as portable language.

C is powerful
C is structure oriented language.
C is not an object oriented programming language.
C can be used to write high level business applications. At the same time it can be used for low level assembly programs. As it can be used for both high level and low level programming it is called as middle level language.

Applications of c:

1. C is basic language for learning advanced languages like c++, java c#.
2. C is used in field of graphics
3. Used for creating system level programming. It is used for creating operating system, compilers.

What is a compiler?

Source code written in a programming language cannot be understood by system. There is an equal binary code for source code. The binary code contain only I’s and 0’s and it can be under stand by system. The role of compiler is to change source code in to machine language.
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