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How to find the last index value of a string in Golang?
LastIndex() is a built-in function of strings package in Golang. This function is used to check the index of the last occurrence of a specified substring in a given original string. If the substring is found in the given string, then it returns its index position, starting from 0; otherwise it returns "-1".
Syntax
The syntax of LastIndex() is −
func LastIndex(str, substr string) int
Where,
- str is the string inside which we need to search, and
- substr is the substring that we want to search inside the str.
Example 1
Let us consider the following example −
package main
import (
"fmt"
"strings"
)
func main() {
// Initializing the Strings
p := "Programming Language"
q := "String Function"
r := "Golang String Function"
s := "1234512345"
// Display the Strings
fmt.Println("String 1:", p)
fmt.Println("String 2:", q)
fmt.Println("String 3:", r)
fmt.Println("String 4:", s)
// Using the LastIndex Function
test1 := strings.LastIndex(p, "ge")
test2 := strings.LastIndex(q, "C")
test3 := strings.LastIndex(r, "ng")
test4 := strings.LastIndex(s, "23")
// Display the LastIndex Output
fmt.Println("LastIndex of 'ge' in String 1:", test1)
fmt.Println("LastIndex of 'C' in String 2:", test2)
fmt.Println("LastIndex of 'ng' in String 3:", test3)
fmt.Println("LastIndex of '23' in String 4:", test4)
}Output
It will generate the following output −
String 1: Programming Language String 2: String Function String 3: Golang String Function String 4: 1234512345 LastIndex of 'ge' in String 1: 18 LastIndex of 'C' in String 2: -1 LastIndex of 'ng' in String 3: 11 LastIndex of '23' in String 4: 6
Observe that LastIndex() is case-sensitive; hence it returns "-1" for test2.
Example 2
Let us take another example.
package main
import (
"fmt"
"strings"
)
func main() {
var x string
var y string
// Intializing the Strings
x = "LastIndex"
y = "LastIndex Function"
// Display the Strings
fmt.Println("String 1:", x)
fmt.Println("String 2:", y)
// See if y is found in x using LastIndex Function
if strings.LastIndex(y, x) != -1 {
fmt.Println("String 2 is found in String 1")
} else {
fmt.Println("String 2 is not found in String 1")
}
}Output
It will generate the following output −
String 1: LastIndex String 2: LastIndex Function String 2 is found in String 1
Updated on: 10-Mar-2022
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