在C#中查找一个较大字符串中所有子字符串的位置

public static Dictionary<string, IEnumerable<int>> GetWordsPositions(this string input, string[] Susbtrings)
{
    Dictionary<string, IEnumerable<int>> WordsPositions = new Dictionary<string, IEnumerable<int>>();
    IEnumerable<int> IndexOfAll = null;
    foreach (string st in Susbtrings)
    {
        IndexOfAll = Regex.Matches(input, st).Cast<Match>().Select(m => m.Index);
        WordsPositions.Add(st, IndexOfAll);

    }
    return WordsPositions;
}

我知道这是旧的，但我想，我会将列表答案转换为整数数组答案（没有在这里看到过）。

    int[] GetPositionsAsArray(string sourceString, string searchString)
    {
        if (String.IsNullOrEmpty(searchString) || String.IsNullOrEmpty(sourceString))
        {
            return new int[] { -1 };
        }
        else
        {    
            int[] ret = new int[sourceString.Length];
            int len = searchString.Length;               
            int index = 0;
            int start = -len;
            while (true)
            {
                start = sourceString.IndexOf(searchString, start + len);
                if (start == -1)
                {
                    break;
                }
                else
                {
                    ret[index] = start;
                    index++;
                }
            }
            Array.Resize(ref ret, index); //optional
            return ret;
        }
    }

 public static class MyExtensions
    {
        public static int HowMany(this string str, char needle)
        {
            int counter = 0;
            int nextIndex = 0;
            for (; nextIndex != -1; )
            {
                nextIndex = str.IndexOf(needle, nextIndex);
                if (nextIndex != -1)
                {
                    counter++;
                    //step over to the next char
                    nextIndex++;
                }
            }
            return counter;
        }
    }

你可以使用LINQ来选择和枚举所有元素，然后通过任何字符串查找：

我已经创建了一个类：

class Pontos 
{
    //index on string
    public int Pos { get; set; }
    //caractere 
    public string Caractere { get; set; }           
}

使用方法如下：

int count = 0;

var pontos = texto.Select(y => new Pontos { Pos = count++, Caractere = y.ToString() }).Where(x=>x.Caractere == ".").ToList();

然后： 输入字符串：

输出列表：

附注： SeForNumero 是我类的另一个字段，我需要它来完成自己的目的，但对于这种使用不是必需的。

我发现了这个示例，并将其合并到一个函数中：

    public static int solution1(int A, int B)
    {
        // Check if A and B are in [0...999,999,999]
        if ( (A >= 0 && A <= 999999999) && (B >= 0 && B <= 999999999))
        {
            if (A == 0 && B == 0)
            {
                return 0;
            }
            // Make sure A < B
            if (A < B)
            {                    
                // Convert A and B to strings
                string a = A.ToString();
                string b = B.ToString();
                int index = 0;

                // See if A is a substring of B
                if (b.Contains(a))
                {
                    // Find index where A is
                    if (b.IndexOf(a) != -1)
                    {                            
                        while ((index = b.IndexOf(a, index)) != -1)
                        {
                            Console.WriteLine(A + " found at position " + index);
                            index++;
                        }
                        Console.ReadLine();
                        return b.IndexOf(a);
                    }
                    else
                        return -1;
                }
                else
                {
                    Console.WriteLine(A + " is not in " + B + ".");
                    Console.ReadLine();

                    return -1;
                }
            }
            else
            {
                Console.WriteLine(A + " must be less than " + B + ".");
               // Console.ReadLine();

                return -1;
            }                
        }
        else
        {
            Console.WriteLine("A or B is out of range.");
            //Console.ReadLine();

            return -1;
        }
    }

    static void Main(string[] args)
    {
        int A = 53, B = 1953786;
        int C = 78, D = 195378678;
        int E = 57, F = 153786;

        solution1(A, B);
        solution1(C, D);
        solution1(E, F);

        Console.WriteLine();
    }

返回：

在位置2找到53

在位置4找到78
在位置7找到78

57不在153786中

基于我用于在较大字符串中查找多个字符串实例的代码，您的代码将如下所示：

List<int> inst = new List<int>();
int index = 0;
while (index >=0)
{
    index = source.IndexOf("extract\"(me,i-have lots. of]punctuation", index);
    inst.Add(index);
    index++;
}