Golang | Finding Index of the Regular Expression present in String Last Updated : 05 Sep, 2019 Comments Improve Suggest changes Like Article Like Report A regular expression is a sequence of characters which define a search pattern. Go language support regular expressions. A regular expression is used for parsing, filtering, validating, and extracting meaningful information from large text, like logs, the output generated from other programs, etc. In Go regexp, you are allowed to find the leftmost index value of the specified regular expression in the given string with the help of the FindStringIndex() method. This method returns a two-element slice of integers which defines the location of the leftmost match in the given string of the regular expression and the match like str[loc[0]:loc[1]]. Or it will return nil if no match found. This method is defined under the regexp package, so for accessing this method you need to import the regexp package in your program. Syntax: func (re *Regexp) FindStringIndex(str string) (loc []int) Example 1: C // Go program to illustrate how to find the // index value of the regexp in the given string package main import ( "fmt" "regexp" ) // Main function func main() { // Finding index regexp // from the given string // Using FindStringIndex() method m := regexp.MustCompile(`ee`) fmt.Println(m.FindStringIndex("GeeksgeeksGeeks, geeks")) fmt.Println(m.FindStringIndex("Hello! geeksForGEEKs")) fmt.Println(m.FindStringIndex("I like Go language")) fmt.Println(m.FindStringIndex("Hello, Welcome")) } Output: [1 3] [8 10] [] [] Example 2: C // Go program to illustrate how to find the index // value of the regexp in the given string package main import ( "fmt" "regexp" ) // Main function func main() { // Finding the regexp // from the given string // Using Find() method m := regexp.MustCompile(`345`) res := m.FindString("I45, like345, Go-234 langu34age") // Finding the index value of regexp in the given string // UsingFindStringIndex() method r := m.FindStringIndex("I45, like345, Go-234 langu34age") fmt.Printf("Found: %s with index value: %d", res, r) } Output: Found: 345 with index value: [9 12] Comment More infoAdvertise with us Next Article Golang | Finding Index of the Regular Expression present in String ankita_saini Follow Improve Article Tags : Go Language Golang Golang-String Similar Reads Go Tutorial Go or you say Golang is a procedural and statically typed programming language having the syntax similar to C programming language. It was developed in 2007 by Robert Griesemer, Rob Pike, and Ken Thompson at Google but launched in 2009 as an open-source programming language and mainly used in Google 2 min read Go Programming Language (Introduction) Go is a procedural programming language. It was developed in 2007 by Robert Griesemer, Rob Pike, and Ken Thompson at Google but launched in 2009 as an open-source programming language. Programs are assembled by using packages, for efficient management of dependencies. This language also supports env 11 min read time.Sleep() Function in Golang With Examples In Go language, time packages supplies functionality for determining as well as viewing time. The Sleep() function in Go language is used to stop the latest go-routine for at least the stated duration d. And a negative or zero duration of sleep will cause this method to return instantly. 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