Logical Operators
These are the ones that allow you to create more elaborate constructs (uh….better stuff than we’ve done so far?)

In PHP, one example of a TRUE condition is simply a variable name that has a value,
such as: $variable = 5;
if ($variable) {…. and so on.

A condition is also TRUE if it make logical sense,
such as: if (5 >= 3) {… and so on

The condition will be FALSE if it refers to a variable that has no value, or if I”ve created an illogical construct,
such as: if (5 <= 3 ) {…. this is obviously wrong, and always will be

In PHP, the exclamation mark (!) is the NOT operator. You can use it to invert the TRUE/FALSE status of a statement,
such as: $var = “value”;

         if ( $var ) {…     this will be TRUE

         if ( ! $var ) {…   this will be FALSE

and written another way:
isset ($var); this will be TRUE
! isset ($var); this will be FALSE

         ! empty ($var);    this will be TRUE

To go beyond simple one-part conditions, PHP supports five more types of logical operators:
two versions of “and” (and and &&)
two versions of “or” (OR and || ) The character “|” is called the pipe,
and you use two together for this.
one version of “or not” (XOR)

When there are two options for any one operator, they differ only in precedence - and can be used interchangeably.

Using parentheses and logical operators you can create even more complex if conditions - for an AND condtion, every part must be TRUE in order for the whole condition to be true, and with OR - only one of the parts of the condition needs to be TRUE.

Nesting Conditions
Conditions can also be nested inside one another (and this can get very confusing, I can tell already).
The key to doing this is to make the interior condition as the “statements” part of the exterior condition,
as so: if ( condition1 ) {

    2 statements;
} else {     this is the statement 2 else
    2 other statements;
}   this is the end of 2

} else { condition 1 else

other statements;

} end of condition 1

Whew! Have to really watch yourself on this, I think!

Two important things to remember:
In order for the statements that are the result of a conditional to be
executed, the conditional must have a TRUE value

By using parentheses, you can ignore rules of precedence, and
    ensure that your operators are addressed in the order that
    you want.

Bunch of stuff to absorb there - need to re-read and get this firmly in my mind.

and that’s my 15 for today! Tomorrow we’ll put this new knowledge to use!