{"id":278,"date":"2024-09-15T17:15:48","date_gmt":"2024-09-15T10:15:48","guid":{"rendered":"https:\/\/gotutorial.org\/?page_id=278"},"modified":"2024-09-15T17:15:49","modified_gmt":"2024-09-15T10:15:49","slug":"go-methods","status":"publish","type":"page","link":"https:\/\/www.gotutorial.org\/go-tutorial\/go-methods\/","title":{"rendered":"Go Methods"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you will learn about Go methods, which allow you to define methods on types including structs.<\/p>\n\n\n\n

Go methods allow you to define functions on types including structs<\/a>. By definition, Go methods are functions<\/a> with a receiver argument.<\/p>\n\n\n\n

Here’s the syntax for defining a method:<\/p>\n\n\n

func<\/span> (r receiverType)<\/span> methodName<\/span>(parameters)<\/span> returnType<\/span><\/span> {\n    \/\/ method body<\/span>\n}<\/code><\/span>Code language:<\/span> Go<\/span> (<\/span>go<\/span>)<\/span><\/small><\/pre>\n\n\n
Go method example<\/h2>\n\n\n\n
Step 1. Define a Rectangle<\/code> struct that has length<\/code> and width<\/code> fields:<\/p>\n\n\n
type<\/span> Rectangle struct<\/span> {\n    length float64<\/span>\n    width  float64<\/span>\n}<\/code><\/span>Code language:<\/span> Go<\/span> (<\/span>go<\/span>)<\/span><\/small><\/pre>\n\n\n
Step 2. Create a function that calculates the area of a Rectangle<\/code> struct:<\/p>\n\n\n
func<\/span> Area<\/span>(r Rectangle)<\/span> float64<\/span><\/span> {\n    return<\/span> r.length * r.width\n}<\/code><\/span>Code language:<\/span> Go<\/span> (<\/span>go<\/span>)<\/span><\/small><\/pre>\n\n\n
Step 3. Create a Rectangle<\/code> struct value, calculate the area, and display the result on the screen:<\/p>\n\n\n
func<\/span> main<\/span>()<\/span><\/span> {\n    r := Rectangle{length: 10<\/span>, width: 5<\/span>}\n    fmt.Println(\"Area of rectangle is\"<\/span>, Area(r))\n}<\/code><\/span>Code language:<\/span> Go<\/span> (<\/span>go<\/span>)<\/span><\/small><\/pre>\n\n\n
Here’s the complete program:<\/p>\n\n\n
package<\/span> main\n\nimport<\/span> \"fmt\"<\/span>\n\ntype<\/span> Rectangle struct<\/span> {\n    length float64<\/span>\n    width  float64<\/span>\n}\n\nfunc<\/span> Area<\/span>(r Rectangle)<\/span> float64<\/span><\/span> {\n    return<\/span> r.length * r.width\n}\n\nfunc<\/span> main<\/span>()<\/span><\/span> {\n    r := Rectangle{length: 10<\/span>, width: 5<\/span>}\n    fmt.Println(\"Area of rectangle is\"<\/span>, Area(r))\n}<\/code><\/span>Code language:<\/span> Go<\/span> (<\/span>go<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
Area of rectangle is 50<\/span><\/code><\/span>Code language:<\/span> Go<\/span> (<\/span>go<\/span>)<\/span><\/small><\/pre>\n\n\n
The program works fine. But it’s more intuitive if we can call the Area()<\/code> function like this:<\/p>\n\n\n
r.Area()<\/code><\/span>Code language:<\/span> Go<\/span> (<\/span>go<\/span>)<\/span><\/small><\/pre>\n\n\n
To do this, we can define the Area()<\/code> function as a method of the Rectangle<\/code> struct type.<\/p>\n\n\n\n
Step 4. Change the Area()<\/code> function to a method:<\/p>\n\n\n
func<\/span> (r Rectangle)<\/span> Area<\/span>()<\/span> float64<\/span><\/span> {\n    return<\/span> r.length * r.width\n}<\/code><\/span>Code language:<\/span> Go<\/span> (<\/span>go<\/span>)<\/span><\/small><\/pre>\n\n\n
In this example:<\/p>\n\n\n\n
In this syntax, you place the receiver argument between the func<\/code> keyword and method name. The rest is the same as the syntax for defining a function<\/a>.<\/p>\n\n\n\n