 In this module, I'll talk about the rad variables, the operators, the types of operators and this is with reference to PHP because the web programming language we'll be using in this course is PHP and with reference to PHP why we are using PHP and how it compares with other environments that I have discussed in the previous module. So PHP is very popular and it doesn't cost a lot of money to host it and it is available and it is not you don't have to pay a very high license fee. So now we go into the nitty gritty details starting with the nitty gritty details about the PHP, how you declare the variables, how you name the variables and what are the types associated with a variable, what is meant by loose types and how you check the types and how you assign the types and how you fix the types of variables and I will also talk about the operators because it's not very interesting if I just have the variables and I load values in the variables and I perform unless I perform interesting operations on the variables it is not very exciting and then finally towards the end of this module I will talk about the precedence of the operators because this application has to understand that if I write an expression with the operators what should be the precedence, what should be the order, what should be the priority, what should be the sequence in which the operators have to be executed so as to get the correct result because at the end of the day it is the correct result, your boss may forgive you for a slow application, your boss may look aside if the application is not giving the desired level of performance but the answer should never be wrong, answer has to be correct 100% of the time all of the time. So what is a variable, a variable is like a container it is called a variable because the contents of that container can change, can vary so it's a variable and the naming convention of PHP is that you put a dollar sign and then you write the variable name and whenever the PHP encounters the variable it understands it is a variable it declares the variable I can create the variables and then is the type of the variable. Now there is a concept which is called as the loose type for PHP, the loose type means that the type of data associated with that variable is not fixed unlike Java where if you declare an integer variable it remains the integer variable but for PHP I declare the integer variable assign an integer value to it and then I add a real value to it it becomes a real variable and then I concatenate with a string to create a longer string it becomes a string variable and of course this not chaos then I can test the type of the variable there are commands which are like get type and then I can change the type of the variable by set type and then by typecasting I can also work with the types of the variable so there is a lot of flexibility over here then look at the commands for testing the type of the variable as you can see over here I can check if it's integer type I can check if it is Boolean type and I can also check that what is the type and application of that variable so then are the operators as I said before that having the operator makes the thing actually work for you so we have these comparison operators error control operators incrementing and decrementing operators these operators are there in the loops and then we have the logical apparatus operators we have the string operators and we have the area operators and the list goes on so we have all those operators and of course we have also functions in PHP which can do a lot of things and there are about 30 or so functions in PHP and of course I will discuss those functions as we come towards the details now this is the list of different operators and they are listing in terms of the precedence precedence means that which operator will work at which priority I give you one example for example if I have 2 plus 3 into 5 2 plus 3 into 5 like it what does it means does it means that 2 plus 3 is 5 into 5 25 or it means 2 plus 3 into 5 which is 15 plus 2 that is 17 so from this table we can see the precedence of the multiplication is higher than the precedence of addition so the correct answer would be the one which in which the multiplication takes place first which is followed by the addition so this is the precedence and of course we will discuss more about it and discuss the details with you