In Swift, constants and variables are declared using the let and var keywords, respectively. The let keyword is used to declare a constant, which is a value that cannot be changed. The var keyword is used to declare a variable, which is a value that can be changed.
When declaring a constant or variable, you must specify its type. The type of a constant or variable is the data type that it can store. For example, the following code declares a constant named myConstant of type Int:
let myConstant: Int = 10
The Int type is a type of integer.
You can also declare a constant or variable without specifying its type. In this case, the type of the constant or variable will be inferred from the value that you assign to it. For example, the following code declares a variable named myVariable and assigns it the value 10. The type of myVariable will be inferred to be Int:
var myVariable = 10
You can use constants and variables to store any type of value, including integers, floats, strings, and Booleans.
Here are some examples of how to use constants and variables:
// Declare a constant to store the number of pages in a book.
let numberOfPages = 200
// Declare a variable to store the name of the book.
var bookName = "The Swift Programming Language"
// Declare a variable to store the current page number.
var currentPageNumber = 1
// Increment the current page number.
currentPageNumber += 1
// Print the current page number.
print(currentPageNumber)
Constants and variables are a fundamental part of programming. They allow you to store values and refer to them later in your code.
Here are some additional things to keep in mind when declaring constants and variables:
- Constants and variables must have unique names.
- Constants and variables cannot be declared with the same name as a keyword.
- Constants and variables cannot be declared with the same name as a function or method.
- Constants and variables cannot be declared with the same name as a type.
