Finding Substring Indices in Strings with PHP

Hello, and welcome to our analysis lesson. In this lesson, we will tackle a common problem in string manipulations with PHP. We will learn how to find all occurrences of a substring within a larger string. The techniques you will master today can be utilized in numerous situations, such as text processing and data analysis. Are you ready to get started? Let's jump right in!

Here is this unit's task: We have two arrays of strings, both of identical lengths — the first containing the "original" strings and the second containing the substrings. Our goal is to detect all occurrences of each substring within its corresponding original string and, finally, return an array that contains the starting indices of these occurrences. Remember, the index counting should start from 0.

Example

Let's consider the following arrays:

• Original Array: ["HelloWorld", "LearningPHP", "GoForBroke", "BackToBasics"]
• Substring Array: ["loW", "ear", "o", "Ba"].

The following are the expected outputs:

• In "HelloWorld", "loW" starts at index 3.
• In "LearningPHP", "ear" starts at index 1.
• In "GoForBroke", "o" appears at indices 1, 3, and 7.
• In "BackToBasics", "Ba" starts at indices 0 and 6.

Thus, when findSubString(["HelloWorld", "LearningPHP", "GoForBroke", "BackToBasics"], ["loW", "ear", "o", "Ba"]) is invoked, the function should return:

[
    "The substring 'loW' was found in the original string 'HelloWorld' at position(s) 3.",
    "The substring 'ear' was found in the original string 'LearningPHP' at position(s) 1.",
    "The substring 'o' was found in the original string 'GoForBroke' at position(s) 1, 3, 7.",
    "The substring 'Ba' was found in the original string 'BackToBasics' at position(s) 0, 6."
]

Although this task may seem fairly straightforward, it can prove challenging. However, don't worry! We will break it down step by step.

Initially, we need to create a space to store our results. Can you think of a PHP data type that would be ideal for this task? That's right! An array would be perfect!

function findSubString($origStrs, $substrs) {
    $result = [];