Welcome back to introduction to Python Scripting. This is the first course in python scripting for dev op specialization. All right, so in this third module of the course, we want to learn how to change the flow of our programs' execution based on the test that's in our code. We call this decision branching, and all programming languages have some form of decision branching. So by the time you're done with this module, I want you to be able to do several things. One of these is develop programs that utilize the F statement. You should also be able to develop programs that utilize if if else statements. And lastly, you should be able to develop programs that utilize the elif statements. All right, so in lesson one, let's first think about boolean expressions, these are expressions that are going to evaluated true or false. So we've seen some operators that we use in expressions earlier. Here, we want to think about relational operators, these operators always evaluate true or false. So the first one in our table in front of you is the equal, and we actually do this with two equal symbols. Okay, that make sure that's clear, because other programming languages only use a single one, and we want to distinguish and python between the relational operator equal, and the assignment operator of the single equal. Okay, so for, if both expressions are true, or both expressions are equal, then the result of the equal operator is true. The next one in our table is not equal. That's the exclamation point in the equal sign, right? So if the two values are not the same, they're not equal, than we have greater than, less than, greater than or equal to, or less than or equal. And you see some examples in the right hand side. We also can combine relational comparisons with logical operators. And we have three here, we have, and, or, and not. And so, for the and operator, both sides of the and have to be true for the and true. So in the example in front of you, you see X is less than five, and X is less than 10. It's probably a trivial example, because if X is less than 10, it's less than five. I'm sorry, if X is less than five then, also, less than 10. Okay, but you get the idea. Both sides have to be true. The next one is an or, only one of the two sides have to be true. Both are true, that's fine, right? So one or more sides is true. So X is less than five or X is less than four. And lastly, the not, not just flips whatever the result was. So if it's true, it makes it false. If it's false, it makes it true. All right, so that's it for boolean expressions. A little review here, relational operators evaluated true or false. Logical operators allow you to build more complicated expressions. And lastly, both operations must be true for the expression to be true with an and operator. All right, see you in the next lesson.
