#Swift handy calculator subtraction how to#
#Swift handy calculator subtraction code#

The difference is that Doubles have more precision than Floats, so they can store longer decimal numbers.

Float and Double вЂ“ these two represent decimal numbers.

Int вЂ“ this is short for вЂњinteger.вЂќ This type represents whole numbers: positive and negative.

The name basically refers to having a string of characters: In Swift, there are several different types of data, but these are the most common ones: I previously mentioned you canвЂ™t change the kind of data a variable stores, as in the following line: str = 20 Most Common Data Types in Swift

#Swift handy calculator subtraction code#

To start, letвЂ™s look at a line of code from the previous chapter: var str = 'Hello, playground'ДЄbove, weвЂ™ve declared a variable called str, and assigned a piece of string or text data to it. In this chapter, weвЂ™ll talk about different data types in Swift.

Constants are like variables, but you canвЂ™t reassign data to them after the initial assignment.Дata in apps can be as simple as text or numbers or as complex as photo data or employee records in a company database.

Use camel case as a best practice for naming your variables and constants.

Use the equal sign to assign data to a variable or constant.

Use the var and let keywords to declare new variables and constants.

Variables and constants are used to keep track of data in your app.

Then, veryfirstname in camel casing would be veryFirstName, which is much easier to read. Camel casing simply means starting the first word with a lowercase letter, and starting every subsequent word with an uppercase letter. Thus, a good capitalization method to use is camel casing. Ideally, a variable name should be one to four words long.ДЄ variable name such as veryfirstname can also be hard to read, though. If they are too short like str, you wonвЂ™t know what kind of data the variable holds. If they are too long, they can get hard to read. ThereвЂ™s a fine balance to upkeep when it comes to the length of your names. I mentioned before that your variable names should be descriptive so you know what kind of data they hold. Best Practices for Naming Variables and Constants In those cases, itвЂ™s simply a matter of changing the var keyword to the let keyword in the variablesвЂ™ declarations. Also, if your program uses variables that never change their data, Xcode will suggest changing the variables into constants instead. Over the course of your Swift journey, youвЂ™ll build a sense of when to use variables versus constants. Despite this, itвЂ™s more preferable in some cases to use constants over variables, like to keep track of data you donвЂ™t intend to change later. Here, Xcode tells me that I cannot assign something else to the constant lastName because it was already assigned the value of вЂњSmithвЂќ.ДЄt this point, it seems that variables are much more flexible than constants. HereвЂ™s how our variable looks in the playground: A complete example of the variable declaration is given below. Since we named this variable вЂњfirstName,вЂќ weвЂ™ll give it a piece of text data, namely the word вЂњTom.вЂќ Note: the single equal sign lets us assign a piece of data to the firstName variable. For example, if I had a piece of data for someoneвЂ™s first name, I might name my variable firstName.ДЇollowing your variable name, add an equal sign and then the piece of data you want to keep track of. You can name it anything you want, but the name should clearly describe the data the variable will contain.

First, type the keyword var, followed by a space, and your variableвЂ™s name.

#Swift handy calculator subtraction how to#

LetвЂ™s learn how to create, or declare, a new variable to track a piece of data in memory. This is where variables come in, to help keep track of data within an app. For us to work with data, we need a way to refer to it in our programs. Your computer stores data in its memory to keep track of where the data is and what it is. We can even have text data like 'Hello' surrounded by double quotes on line 5. Data can be numbers like 123 and the decimal 0.7 as shown on lines 3 and 4. The national prefix was removed from the number.Here, we have different types of data. (The entered number already included the area code) (If you are behind a switchboard you may have to dial '0' or '9' (or another number) to get an external line.) How the number is composed NumberД 0 is the international prefix used to dial somewhere outside of Qatar.Д©71 is the international code used to dial to United Arab Emirates.Д¤ is the local area or city code used to dial to Dubai. Dialing from Doha to Dubai Result, dial: 00 971 This service will soon be scrapped, but we still offer loads of other handy calculators. Business Date to Date (exclude holidays).