Difference between revisions of "PHP-and-MySQL/C2/Logical-Operators/English-timed"

|What is a '''logical operator'''? Let's add a bit of logic and say it's the '''AND''' or the '''OR''' operator.   

|Now, if I start creating my basic layout for my '''if''' statement, I will get to work on showing you what you can do with these.  

|Before we had example such as '1 is greater than 1' which at the moment is going to return '''False'''

|Let's just check it to see where we are.... right!. So that's "False".

|Now, what if I said "if 1 is greater than 1 or equals 1".

|Now we don't write it as 'OR', we write it as two vertical lines or two pipes.

|So, if we compile this, what do you think the result is gonna be?  

|Now let's run through this once - '''if 1 is greater than 1''' - "false" and so we have written "false" or 1 is equal to 1...

|We know that '''1 equals to 1''' is "true". So, here we are saying '''OR''' 1 is equal to 1, not '''AND'''; because if we said '''AND''' then both would have to be "true".  

| '''OR''', either of these could be "true" to make this.

|Okay, so that's the '''OR'''.

|Basically it allows you to take two comparisons, show them in your '''if''' statement and if either of them is "true" - then it's like an either operator...

|either of them are "true", you will be left with "true".

|''''AND' operator''' is a different manner.

|'''AND''' requires both of these to be "true" for this to be executed.  

|So, we have got "false" here because 1 is not greater than 1.

|We'll go back to our comparison operators and we will say "if 1 is greater than 1 or equal to 1 '''AND''' (&&) 1 equal 1", here we will get "true".  

|But I am pretty sure that you have got the hang of variables by now by following my other tutorials.

|So, these are the two '''logical operators'''.

|You will find them very useful because you might want to say, for example, this is a very classic example; you'll find it in one of my projects.

|It is a "login" '''form'''.  Say, a user wants to 'login' into a website.

|So, we can say, for example:

|If the username, in fact let's do this, I'll say '$username' is equal to "alex" and my '$password' is equal to "abc".

|Now, I will substitute these. I can say "username" '''AND''' (&&) "password".  

|At the moment, this will say "True".

|I'll change this.  I'll say "OK" or "you forgot to fill out a field" because there will eventually be '''HTML fields'''.

|So, let's try it. Yes, that's saying "OK".

|Now what happens if I forget to type my password in there? There's nothing in there at the moment - no space - let's get rid of that.  

|"You forgot to fill out a field".

|So, if you imagine these are coming from the user - so it has been submitted as you typed your "username" and "password" in.

|We'll just check that, there you go.

|So, because we have got "username" and "password" then that's fine.

|But for the 'OR' that doesn't really make sense and you can imagine what will happen.

|So right now, this will equal "true" because we have got both values.  So this is "OK".

|Now, if I go with both of them and try it out.

|If the username exists, so the username is "True"...

|At the moment there is no value - so it is "False".  

|or the password is true - that is the value exists, at the moment it doesn't, so it is "False".  

|So, we are going to say  "You forgot to fill out a field".

|I'll just write here "Nothing" because at the moment it means nothing.

|So '''refresh'''. I'll make it "Nothing".  

|So you see, already I have explained how useful these can be in so many every day '''php applications'''.

|Two operators that are '''logical operators'''.

|This is Sidharth, dubbing for the Spoken Tutorial project.