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

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

Answer

To find the indices of all occurrences of a substring in Swift, you can use the range(of:) method in a loop to find all occurrences and store their indices in an array.


✐ Examples

1 Find Indices of All Occurrences in String

In this example,

  1. We create a string variable str with a string value.
  2. We create an array to store indices.
  3. We use a loop with the range(of:) method to find all occurrences of a specific substring within str and store their indices in the array.
  4. We print the array of indices.

Swift Program

import Foundation

let str = "Hello Hello Hello"
let substr = "Hello"
var indices: [Int] = []
var searchStartIndex = str.startIndex
while let range = str.range(of: substr, range: searchStartIndex ..< str.endIndex) {
    let index = str.distance(from: str.startIndex, to: range.lowerBound)
    indices.append(index)
    searchStartIndex = range.upperBound
}
print("Indices of all occurrences:", indices)

Output

Indices of all occurrences: [0, 6, 12]

2 Find Indices of All Occurrences in Another String

In this example,

  1. We create two string variables str1 and str2 with different values.
  2. We create an array to store indices.
  3. We use a loop with the range(of:) method to find all occurrences of str2 within str1 and store their indices in the array.
  4. We print the array of indices.

Swift Program

import Foundation

let str1 = "apple banana cherry banana"
let str2 = "banana"
var indices: [Int] = []
var searchStartIndex = str1.startIndex
while let range = str1.range(of: str2, range: searchStartIndex ..< str1.endIndex) {
    let index = str1.distance(from: str1.startIndex, to: range.lowerBound)
    indices.append(index)
    searchStartIndex = range.upperBound
}
print("Indices of all occurrences:", indices)

Output

Indices of all occurrences: [6, 20]

Summary

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


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