C#委托—马工教你轻松玩转委托

一、实现步骤

1. 遍历主字符串，使用IndexOf方法查找子字符串的位置。
2. 如果找到了子字符串，记录其位置，并且从该位置的后面继续查找。
3. 重复上述步骤直到遍历完整个字符串。

二、简单代码示例

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {
        string mainString = "Here is a test string, and here is another test string.";
        string substring = "test";
        var positions = FindAllSubstringPositions(mainString, substring);

        Console.WriteLine(
using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {
        string mainString = "Here is a test string, and here is another test string.";
        string substring = "test";
        var positions = FindAllSubstringPositions(mainString, substring);

        Console.WriteLine($"The substring '{substring}' is found at positions: {string.Join(", ", positions)}");
    }

    static List<int> FindAllSubstringPositions(string mainString, string substring)
    {
        List<int> positions = new List<int>();
        int index = mainString.IndexOf(substring, StringComparison.Ordinal);

        while (index != -1)
        {
            positions.Add(index);
            // Move to the next character after the found substring to avoid overlapping matches.
            index = mainString.IndexOf(substring, index + substring.Length, StringComparison.Ordinal);
        }

        return positions;
    }
}
quot;The substring '{substring}' is found at positions: {string.Join(", ", positions)}");
    }

    static List<int> FindAllSubstringPositions(string mainString, string substring)
    {
        List<int> positions = new List<int>();
        int index = mainString.IndexOf(substring, StringComparison.Ordinal);

        while (index != -1)
        {
            positions.Add(index);
            // Move to the next character after the found substring to avoid overlapping matches.
            index = mainString.IndexOf(substring, index + substring.Length, StringComparison.Ordinal);
        }

        return positions;
    }
}

中，FindAllSubstringPositions 方法使用IndexOf方法来查找子字符串的位置。如果找到了子字符串，它将位置添加到列表中，然后从找到的位置的后面继续搜索，以避免重复计数。这个过程一直持续到整个主字符串都被检查完毕。

请注意，IndexOf方法的第三个参数允许你指定搜索的起始位置，这使得我们可以在找到子字符串后从正确的位置继续搜索。StringComparison.Ordinal确保比较是基于原始字符串的字符顺序，不考虑文化或区域设置。