 So students in this module, I will be covering the text from the operators to the constants and which operators I will be covering string operators, all right. So let's go into the detail and look at the module coverage. So look at the string operators, look at the precedence of the operators means that which operator will be operated upon before the other operator if there are multiple operators in the expression. So that is the operator precedence and then the constant. So there's a purpose why I have shown this constant in capital letters which I will very shortly explain and then look at a very simple example in which what we have learned that will be used and show you the results. Let's go ahead string operator is represented by a dot which is the concatenation operator as you can see on your screen. This is very interesting example over here. I have declared a variable temperature in Fahrenheit which is an integer variable. And then I have this concatenation operator over here and this concatenation operator over here also. And then over here there is an expression which is evaluated, there is an expression which is evaluated. So what we see over here is that we get a result, this result we get, all right. So we have the concatenation. We have the result which was a mathematical operation which was converted into a string because of the concatenation operator. I believe you understand this, okay. And then we have this combined assignment over here which is like a shorthand for this which I have already explained before also. It works like a shorthand so this is the power of PHP. Now let's look at operator precedence. What is the meaning of operator precedence? So if I have tried to understand if I have 3 plus 5 into 2. So the answer should be 13 or the answer should be 16. What should be the answer? That is the question, okay. Because if this has a higher precedence then I get 10 plus 3, 13. But if this has a higher precedence then I get 5 plus 3, 8 into 2, 16. So which is the correct answer? Now we cannot leave these things to be processed ambiguously. So this is the operator precedence. So you can see over here that increment and decrement has the highest precedence, right. And we can see over here is that not as then the precedence and this over here, these have a higher, this is higher, see, higher as compared to this is lower, right. So you see that the multiplication has a higher precedence therefore this is going to be the correct answer, not this. Now there is something interesting over here is that this is and over here and this is also and over here. And then there is something more interesting that we have or over here and this or over here. So what is the difference? What is the difference? The difference is in the notation double M percent has a higher precedence as compared to N and this has a higher precedence as compared to R, okay. Now this can become very clear using certain examples but that kind of a coverage, that level of coverage is not as per the scope of this course but it is to give you an idea. So what we see over here that we have two logical operators, okay. We have the two logical ends and we have the two logical hours also and how they differ, they differ based upon their precedence and what is the precedence? Which operator is going to be used first? So of course in the context of arithmetic operators we can use the parenthesis to change the order of precedence for the mathematical operators. Over here I don't go into more detail. Let's talk about constants. So unlike the variables the constants value does not changes. It remains the same throughout the program. It does not change and how a constant is differentiated from a variable it is without this dollar sign. And don't use reserved words, for example don't use get, don't use post, don't use eco, okay. And it can only contain scalar values. Usually the constants are denoted using uppercase letters so it's a convention. Of course you know that PHP's case sensitive you can have a constant name in lower case also but it will be different from the constant name in uppercase and this is how you define the constant as it is shown over here. So I think it becomes very clear. So let's look at one example over here. So I have this variable which is the radius. I assign it the value of 4 and the diameter is twice the value of the radius, okay. And then I have the circumference over here, the circumference and this is a PHP constant. M underscore pi, okay. So I have this echoed over here. This is a circle, circle has a radius and where does this come radius, radius comes from here. And it has a diameter it comes from here, okay. And the circumference is evaluated it comes from over here, right. And this is the way in which this example is evaluated and the results are displayed on the screen and this over here students is all dynamic. This is dynamic stuff. This is all dynamic. I can change the radius and everything changes. That's all I have in this module for you.