How Can I Find All Occurrences of a Substring in a String Using C#?

Finding All Positions of a Substring in a Larger String in C#

The task of finding all occurrences of a specific substring within a larger string is a common challenge in programming. In C#, the IndexOf method provides a straightforward approach, yet it fails to capture multiple instances of the substring.

A better alternative is to leverage an extension method. Here's an implementation:

public static List<int> AllIndexesOf(this string str, string value)
{
    if (String.IsNullOrEmpty(value))
        throw new ArgumentException("the string to find may not be empty", "value");

    List<int> indexes = new List<int>();
    for (int index = 0;; index += value.Length)
    {
        index = str.IndexOf(value, index);
        if (index == -1)
            return indexes;
        indexes.Add(index);
    }
}

To use this extension method, simply import the namespace it resides in and invoke it directly on the string:

List<int> indexes = "fooStringfooBar".AllIndexesOf("foo");

This method efficiently identifies all instances of the substring in the larger string, providing a comprehensive list of their positions.

The above is the detailed content of How Can I Find All Occurrences of a Substring in a String Using C#?. For more information, please follow other related articles on the PHP Chinese website!