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What is Variable?


In our School life , we have seen something like a + b = c where,
                                                                                 a = 8,
                                                                                 b = 2 , so c = ?

Well we can solve this mathematical problem , right ? But what if we want to solve the same problem throughout any Programming language , then something called "var" came to picture . So take a seat , and let's start ..

  In Programming language, if we want to adding two digits for example 3 + 5 and want to print it , we can print also .. But we have to store his two digits somewhere , right ? Let we store 3 into x , and 5 into y . So x = 3 , and y = 5 .But how machine will know or can recognize them ? For this reason variable is came .

   Variable is a factor or element which can store or vary any type of value , it maybe floating type or character type etc . So should we called it Variable or Variable , it will be Variable .
 
  Now in different Programming languages it comes into different way . 
For example : if we go through C language , we have to mention type of the value which is nothing but some predefined keywords , let's see an example below :  


In the above example , we have declared a variable called "a" , and this is integer type variable so we have written the keyword "int" which is present in C library . And then we have initialized it with value 5 .
 Also I have shown u some common datatypes in C .

   In case of JavaScript,we just have to put a keyword called "var" . But we don't have to put data type.Let's see with an example below :


   But in case of PHP , we don't have to mention datatype before declaring it , Cause PHP is so smart after all ..We just have to put "$" sign before variable name. Let's see with an example below:



 So there are many Programming languages and their are different way to declare a variable . I have just given example of C ,JavaScript and PHP .

  So Variable's value is not permanent , I mean we can modify anytime depending on situation .For example , $a = 5 ; so now "a" is holding value 5 but if we want to store 7 into "a" then it will replace with value 5 .But what if we want to initialize a value permanently according to Program requirement , in that case "Constant" is comes into picture  . Let's just see an example below : 


 Here "const" is a predefined keyword which indicates PI ( variable ) is a costant type of double type variable. Floating is nothing but a data type .
So I hope you understand today's topic .Practice more..

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