Variables in C

Just like any other programming languages, C also has variables.
If you do not know already, a variable is a storage location for several types of values.
There are 4 basic types of variable type specifiers in C, according to Wikipedia :

-char
-int 
-float 
-double

 
which can be combined with optional specifiers :

-signed 
-unsigned 
-short 
-long


In total, there are 28 basic data types in C. Here is the complete list along with the description: http://en.wikipedia.org/wiki/C_data_types

The syntax to declare a variable in C is simple, which is :

data_type var_name = initial_value;

Let's see how we use it in a C source code:

#include <stdio.h>
#include <stdlib.h>

int main(){
//declaring the variables
int a = 5;
int b = 2;
int c = a + b;
//printing the value of c, which is a+b, or 5+2
printf("%d",c);
//printing a new line
printf("\n");
//pausing the program to see the result
system("Pause");
return 0;
}

If you can see, I wrote several lines of words using a "//" sign in front. They are called comments. Comments will not be run by the compiler, they are only used to aid programmers to understand the source code. More about comments in the next post.

From the code you can see that I declared an Integer a with the initial value of 5 and Integer b with the initial value of 2. I then declared another Integer c with the value of a + b. Next, I print out the result, which is the value of c using printf.
You can also use other data types for different operations. Let's do division with integer and float data types for example. Here is the code :

#include <stdio.h>
#include <stdlib.h>

int main(){
//declaring the variables
float a=5;
int b=2;
float c=a/b;
//printing the value of c, which is a/b, or 5/2
printf("%f",c);
//printing a new line
printf("\n");
//pausing the program to see the result
system("Pause");
return 0;
}

The code is pretty much the same, with small modifications here and there.
If you notice, we cannot use integers as the dividend here. Why?
An Integer will always be a non-decimal number, which will give you a wrong result of the division if you declare a or c, or both, as an Integer. Ex : 5/2 = 2.

There you go. Now you can apply variables in your codes. Congratulations !
 


Happy Coding,
Cyber Frost

Basic Structure of C Programs

Every programming language has its basic structure, that is, how and where the lines of code are written.

In C, it looks like this :

#include <stdio.h>

int main(){
    //statement1;
    //statement2;
    //..........;
return 0;
}

Let's start from the top.

The #include statement is used for including a header file into your program. In this case, stdio.h.
It must precede any other lines of code in your source file.
The int is a return type specifier for the function main(). Every C program must have a main() function in order to run. Even though your program has a thousand lines of code, it will start by executing the main() function.

More about return type of main():
The main() function returns 0. which is an int as an indicator to the compiler that the program was well-executed (without error).

Then, there are these symbols, the {parentheses}, to indicate the start and the end of the main() function. Every line of code, or statement, within the parentheses must be followed by a semicolon (;).

Finally, there is the return statement, which pretty much describes its function already : to return a value from the function it represents. In this case, it is the main() function.

The End. By now you should have the basic knowledge to start writing codes in C.



Happy Coding,
Cyber Frost

Coding in C using Dev-Cpp IDE

Greetings, fellow coders.

Today, I am going to show you an open-source application which enables easy coding and compiling of C programs. It is named Dev-Cpp or Dev-C++, which can be used as an IDE(Integrated Development Environment) to code and to compile C++ as well as C programs.

You can get a free copy of it here :  http://www.bloodshed.net/dev/devcpp.html

After you downloaded and installed Dev-Cpp on your computer, run the devcpp.exe file.

After the splash screen you will see :

Simply close the Tip of the Day window and we shall continue.

At the top left of Dev-Cpp, you will see the File menu, click on it to start a new Project or Source.

Let's try to create a C source file.
Click on File>New>Source File. A new tab will open up, like this :

 

Now type in this code to the code editor:

#include <stdio.h>
#include <stdlib.h>

int main(){
 printf("Hello World\n");
 system("Pause"); 
 return 0;  
}

 Done? Now click the Execute menu and choose Compile & Run or simply press F9.
 It will then ask you to save the source file first. Just save it wherever you desire, but make sure it is in the C source files (*.c) format.
 After saving, a window will show up, looking like this :

Congratulations, you have successfully created a C program using Dev-Cpp !

On the next few posts, I will be giving tutorials on creating C programs with this user-friendly IDE.




Happy Coding,
Cyber Frost