[MUSIC] Up to now we've been making strings using the plus sign to just concatenate the parts of the string we wanted to create. And we've used the str function to convert numbers into strings so that we can concatenate them, too. This works, but it's not ideal, especially when the operations you want to do with the string or on the tricky side. There's a better way to do this using the format method. Let's see a couple of examples. In this example, we have two variables, name and number. We generate a string that has those variables in it by using the curly brackets placeholder to show where the variables should be written. We then pass the variables as a parameter to the format method. See how it doesn't matter that name is a string and number is an integer? The format method deals with that, so we don't have to. Pretty neat, right? The curly brackets aren't always empty. By using certain expressions inside those brackets, we can take advantage of the full power of the format expression. Heads up, this can get complex fast. If at any point, you get confused, don't panic, you only really need to understand the basic usage of the format method we just saw. One of the things we can put inside the curly brackets is the name of the variable we want in that position to make the whole string more readable. This is particularly relevant when the text can get rewritten or translated and the variables might switch places. In our earlier example, we could rewrite the message to make the variables appear in a different order. In that case, we'd need to pass the parameters to format in a slightly different way. Because we're using placeholders with variable names, the order in which the variables are passed to the format function doesn't matter. But for this to work, we need to set the names we're going to use and assign a value to them inside the parameters to format. And that's just the tip of the iceberg of what we can do with the format method. Want to dive a little deeper? Great, let's keep on going. We're going to check out a different example. Let's say you want to output the price of an item with and without tax. Depending on what the tax rate is, the number might be a long number with a bunch of decimals. So if something costs $7.5 without tax and the tax rate is 9%, the price with tax would be $8.175. First off, ouch, and also, since there's no such thing as half a penny anymore, that number doesn't make sense. So to fix this we can make the format function print only two decimals, like this. In this case between the curly brackets we're writing a formatting expression. There are a bunch of different expressions we can write. These expressions are needed when we want to tell Python to format our values in a way that's different from the default. The expression starts with a colon to separate it from the field name that we saw before. After the colon, we write .2f. This means we're going to format a float number and that there should be two digits after the decimal dot. So no matter what the price is, our function always prints two decimals. Remember when we did the table to convert from Fahrenheit to Celsius temperatures? Our table looked kind of ugly because it was full of float numbers that had way too many decimal digits. Using the format function, we can make it look a lot nicer. In these two expressions we're using the greater than operator to align text to the right so that the output is neatly aligned. In the first expression we're saying we want the numbers to be aligned to the right for a total of three spaces. In the second expression we're saying we want the number to always have exactly two decimal places and we want to align it to the right at six spaces. We can use string formatting like this to make the output of our program look nice and also to generate useful logging and debugging messages. Over the course of my sysadmin career, I've grown used to formatting strings to create more informative error messages. They help me understand what's going on with a script that's failing. There's a ton more formatting options you can use when you need them. But don't worry about learning them all at once, we'll explain any others as they come along and we'll put everything in a cheat sheet that you can refer to whenever you need a formatting expression. Let's take a look at that now and then we'll have a quiz to help you get more familiar with all this new knowledge.
