How to find the Indices of All Occurrences of Substring in Go - Step by Step Examples

How to find the Indices of All Occurrences of Substring in Go ?

Answer

To find the indices of all occurrences of a substring in Go, you can iterate through the string and use the strings.Index function.

✐ Examples

1 Find Indices of All Occurrences of Substring in String

In this example,

We import the fmt and strings packages.
We define a function named findAllIndices that takes two strings, str and substr, as parameters.
We initialize an empty slice of integers named indices to store the starting indices of each occurrence of the substring.
We use a loop to search for the substring within the string using the strings.Index function, starting from a given index.
Inside the loop, we append the found index to the indices slice and update the starting index for the next search to be after the current occurrence.
The loop continues until no more occurrences are found.
We return the indices slice.
In the main function, we define a string str and a substring substr with specific values.
We call the findAllIndices function with str and substr and store the result in the variable indices.
Finally, we print the indices to standard output.

Go Program

package main

import (
    "fmt"
    "strings"
)

func findAllIndices(str, substr string) []int {
    var indices []int
    index := strings.Index(str, substr)
    for index != -1 {
        indices = append(indices, index)
        index = strings.Index(str[index+len(substr):], substr)
        if index != -1 {
            index += indices[len(indices)-1] + len(substr)
        }
    }
    return indices
}

func main() {
    str := "Hello World, Hello Universe, Hello Go"
    substr := "Hello"
    indices := findAllIndices(str, substr)
    fmt.Println("Indices of all occurrences:", indices)
}

Output

Indices of all occurrences: [0 13 29]

2 Find Indices of All Occurrences of Another Substring

In this example,

We import the fmt and strings packages.
We use the same findAllIndices function to find all occurrences of a substring within a string.
In the main function, we define a different string str and a different substring substr with specific values.
We call the findAllIndices function with str and substr and store the result in the variable indices.
Finally, we print the indices to standard output.

Go Program

package main

import (
    "fmt"
    "strings"
)

func findAllIndices(str, substr string) []int {
    var indices []int
    index := strings.Index(str, substr)
    for index != -1 {
        indices = append(indices, index)
        index = strings.Index(str[index+len(substr):], substr)
        if index != -1 {
            index += indices[len(indices)-1] + len(substr)
        }
    }
    return indices
}

func main() {
    str := "Go is great. Go is fast. Go is fun."
    substr := "Go"
    indices := findAllIndices(str, substr)
    fmt.Println("Indices of all occurrences:", indices)
}

Output

Indices of all occurrences: [0 13 25]

Summary

In this tutorial, we learned How to find the Indices of All Occurrences of Substring in Go language with well detailed examples.

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