{"id":182,"date":"2024-09-11T13:50:41","date_gmt":"2024-09-11T06:50:41","guid":{"rendered":"https:\/\/gotutorial.org\/?page_id=182"},"modified":"2024-09-11T13:52:15","modified_gmt":"2024-09-11T06:52:15","slug":"go-break","status":"publish","type":"page","link":"https:\/\/www.gotutorial.org\/go-tutorial\/go-break\/","title":{"rendered":"Go Break"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you will learn how to use the Go break statement to exit a loop prematurely.<\/p>\n\n\n\n

Introduction to the Go break statement<\/h2>\n\n\n\n

In Go, the break<\/code> statement allows you to exit a loop prematurely:<\/p>\n\n\n

break<\/span><\/code><\/span>Code language:<\/span> Go<\/span> (<\/span>go<\/span>)<\/span><\/small><\/pre>\n\n\n
Typically, you terminate the loop based on a condition, therefore, you often use the break<\/code> with an if statement<\/a> like this:<\/p>\n\n\n
if<\/span> condition {\n   break<\/span>\n}<\/code><\/span>Code language:<\/span> Go<\/span> (<\/span>go<\/span>)<\/span><\/small><\/pre>\n\n\n
For example, the following shows how to use the break<\/code> statement to terminate a loop that finds the first occurrence of the letter o<\/code> in the string \"Hello World\"<\/code>:<\/p>\n\n\n
package<\/span> main\n\nimport<\/span> \"fmt\"<\/span>\n\nfunc<\/span> main<\/span>()<\/span><\/span> {\n\tmessages := \"Hello World\"<\/span>\n\tfor<\/span> index, value := range<\/span> messages {\n\t\tif<\/span> value == 'o'<\/span>  {\n\t\t\tfmt.Printf(\"The letter o found at the index %d\\n\"<\/span>, index)\n\t\t\tbreak<\/span>\n\t\t}\n\t}\n}<\/code><\/span>Code language:<\/span> Go<\/span> (<\/span>go<\/span>)<\/span><\/small><\/pre>\n\n\n
How it works.<\/p>\n\n\n\n
First, declare a message<\/code> variable and initialize its value to \"Hello World\"<\/code>:<\/p>\n\n\n
messages := \"Hello World\"<\/span><\/code><\/span>Code language:<\/span> Go<\/span> (<\/span>go<\/span>)<\/span><\/small><\/pre>\n\n\n
Second, iterate over each character in the string messages using a for range<\/code> loop:<\/p>\n\n\n
for<\/span> index, value := range<\/span> messages {<\/code><\/span>Code language:<\/span> Go<\/span> (<\/span>go<\/span>)<\/span><\/small><\/pre>\n\n\n
Third, display the index of the first occurrence of the letter o<\/code> and terminate the loop prematurely using the break<\/code> statement:<\/p>\n\n\n
if<\/span> value == 'o'<\/span>  {\n\tfmt.Printf(\"The letter o found at the index %d\\n\"<\/span>, index)\n\tbreak<\/span>\n}<\/code><\/span>Code language:<\/span> Go<\/span> (<\/span>go<\/span>)<\/span><\/small><\/pre>\n\n\n
If we don’t use the break<\/code> statement, the for range<\/code> loop will run till the last character of the string Hello World<\/code>.<\/p>\n\n\n\n
Using Go break statement with a label<\/h2>\n\n\n\n
The break<\/code> statement accepts an optional loop label:<\/p>\n\n\n
break<\/span> LoopLabel<\/code><\/span>Code language:<\/span> Go<\/span> (<\/span>go<\/span>)<\/span><\/small><\/pre>\n\n\n
In practice, you use the break<\/code> statement with a label when you want to stop inner and outer loops. For example:<\/p>\n\n\n
package<\/span> main\n\nimport<\/span> \"fmt\"<\/span>\n\nfunc<\/span> main<\/span>()<\/span><\/span> {\n\tmatrix := [][] int<\/span> {\n\t\t{1<\/span>, 2<\/span>, 3<\/span>},\n\t\t{4<\/span>, 5<\/span>, 6<\/span>},\n\t\t{7<\/span>, 5<\/span>, 5<\/span>},\n\t}\n\t\t\n    target := 5<\/span>\n\n    search:\n    for<\/span> i := 0<\/span>; i < len<\/span>(matrix); i++ {\n        for<\/span> j := 0<\/span>; j < len<\/span>(matrix[i]); j++ {\n            if<\/span> matrix[i][j] == target {\n                fmt.Printf(\"Found %d at (%d, %d)\\n\"<\/span>, target, i, j)\n                break<\/span> search\n            }\n        }\n    }\n}<\/code><\/span>Code language:<\/span> Go<\/span> (<\/span>go<\/span>)<\/span><\/small><\/pre>\n\n\n
How it works.<\/p>\n\n\n\n
First, declare and initialize a two-dimensional array:<\/p>\n\n\n
matrix := [][] int<\/span> {\n    {1<\/span>, 2<\/span>, 3<\/span>},\n    {4<\/span>, 5<\/span>, 6<\/span>},\n    {7<\/span>, 5<\/span>, 5<\/span>},\n}<\/code><\/span>Code language:<\/span> Go<\/span> (<\/span>go<\/span>)<\/span><\/small><\/pre>\n\n\n
Second, declare and initialize a variable that holds a value to search:<\/p>\n\n\n
target := 5<\/span><\/code><\/span>Code language:<\/span> Go<\/span> (<\/span>go<\/span>)<\/span><\/small><\/pre>\n\n\n
Third, iterate over the elements of the matrix using two for loops<\/a> to find the number 5:<\/p>\n\n\n
search:\nfor<\/span> i := 0<\/span>; i < len<\/span>(matrix); i++ {\n\tfor<\/span> j := 0<\/span>; j < len<\/span>(matrix[i]); j++ {\n    \tif<\/span> matrix[i][j] == target {\n        \tfmt.Printf(\"Found %d at (%d, %d)\\n\"<\/span>, target, i, j)\n            break<\/span> search\n        }\n    }\n}<\/code><\/span>Code language:<\/span> Go<\/span> (<\/span>go<\/span>)<\/span><\/small><\/pre>\n\n\n
Before the loop, we declare the search<\/code> label for using with the break<\/code> statement. Inside the loops, when we come across an element with the value 5, we stop both inner and outer loops using the break search<\/code> statement.<\/p>\n\n\n\n
Summary<\/h2>\n\n\n\n
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  • Use the break<\/code> statement to terminate a loop immediately.<\/li>\n<\/ul>\n
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