Program Explanation

Hi Friend , Thanks to coming once again

In any programming it’s very important to explain your code not only for you but also other who are interested in your code. So, in any programming language you can explain your code using COMMENTS. Comments are critical for all but the most trivial programs and this tutorial will often use them to explain sections of code. When you tell the compiler a section of text is a comment, it will ignore it when running the code, allowing you to use any text you want to describe the real code. To create a comment in C, you enter the text with /* and then */ to block off everything between as a comment. Certain compiler environments or text editors will change the color of a commented area to make it easier to spot, but some will not. Be certain not to accidentally comment out code (that is, to tell the compiler part of your code is a comment) you need for the program. When you are learning to program, it is also useful to comment out sections of code in order to see how the output is affected.

So let’s start the programming

Variables

Many times you need to interact with the user, it means that need to take input from user, but before you take input you have a place to store it. The variables are nothing but the name of place in memory where the input data is stored. There are several different types of variables; w hen you tell the compiler you are declaring a variable, you must include the data type along with the name of the variable. Several basic types include char, int, and float. Each type can store different types of data.

A variable of type char stores a single character, variables of  type int store integers (numbers without decimal places), and variables of type float store numbers with decimal places. Each of these variable types - char, int, and float - is each a key word that you use w hen you declare a  variable. Some variables also use more of the computer's memory to store their values.

It may seem strange to have multiple variable types when it seems like some variable types are redundant. But using the right variable size can be important for making your program efficient because some variables require more memory than others. For now, suffice it to say that the different variable types will almost all be used! 

Before you can use a variable, you must tell the compiler about it by declaring it and telling the compiler about what its "type" is. To declare a variable you use the syntax <variable type> <name of variable>;. (The brackets here indicate that your replace the expression with text described within the brackets.) For instance, a basic variable declaration might look like this:

int myvariable

Note once again the use of a semicolon at the end of the line. Even though we're not calling a function, a semicolon is still required at the end of the "expression". This code would create a variable called myVariable; now we are free to use myVariable later in the program. 

It is permissible to declare multiple variables of the same type on the same line; each one should be separated by a comma. If you attempt to use an undefined variable, your program will not run, and you will receive an error message informing you that you have made a mistake. 

Here are some variable declaration examples:

int x;

int a,b,c;

char letter

float the_float

While you can have multiple variables of the same type, you cannot have multiple variables with the same name. Moreover, you cannot have variables and functions with the same name. 

A final restriction on variables is that variable declarations must come before other types of statements in the given "code block" (a code block is just a segment of code surrounded by { and }). So in C you must declare all of your variables before you do anything else: