C language chapter-3.comments

•      Comments are the text which will not be compiled by the compiler. It will just ignore them.

•      Comments are used to give documentation to the program

•      When we will revisit our program after sometime or any other programmer visit your program they must understand what is the purpose of the code.

Example

/* this print output on the screen*/

Starts with /*

Ends with */

Multi line comment

/* this is

Example for

multiline comment */

End line comment

Printf(“hello world”); /*prints output */

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C chapter-2. How to write simple c program by using code blocks.

First open your code blocks IDE.

File->new project.

Dbl click console application

Next select c from the list.

Click next and give name to your project.for example “helloworld”

Click next select Gnu Gcc compiler in the list

Click finish

Next from left side under helloworld project expand “sources”

Dbl click main.c.

#include <stdio.h>

int main()

{

    printf("Hello world!\n");

    return 0;

}

Main() is the function which will be executed first. In any language main function would be the first to be executed. Printf() is a function used to display message passed to it on the console. We mention main as int main because it returns 0 an integer value.

Stdio.h is a header file. Usually header files contains library functions. Stdio.h contains printf(),scanf() functions. So we must import to our program to execute printf()   function. #include is used to import library functions.

Output

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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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