在C＃中第n次出现特定字符时拆分字符串 [英] Split string at nth occurrence of specific character in C#

问题描述

亲爱的所有人，





我想在特定情况下吐出字符串'，'

我的字符串是-1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23， 24,25,26,27,28,29,30



i希望将这个字符串分成3个部分，即在第10次出现'，'后，它应该返回一个string



所以我的第一个字符串是 - 1,2,3,4,5,6,7,8,9,10

和下一个将是 - 11到20等等



但是如果我将字符串拆分为'，'。它只从字符串中分离出1。

有什么建议吗？

Dear All,


I want to spit string at specific occurrence of ','
My string is- 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30

i want to separate this string in 3 parts i.e. after 10th occurrence of ',', it should return a string

so my first string will be - 1,2,3,4,5,6,7,8,9,10
and next will be - 11 to 20 and so on

but if i split string at ','. it only separate "1" from string.
Any suggestions?

推荐答案

另一种方法。因为尽可能少的内存使用，没有字符串重新分配，没有正则表达式。可以改进吗？ :)

Yet another approach. As less memory usage as possible, no string reallocation, no regexp. Could be improved? :)

public IEnumerable<string> SplitBy(string input, char separator, int n)
{
    int lastindex = 0;
    int curr = 0;

    while(curr < input.Length)
    {
        int count = 0;
        while(curr < input.Length && count <n)
        {
            if(input[curr++] == separator) count++;
        }
        yield return input.Substring(lastindex,curr-lastindex-(curr < input.Length ? 1 : 0));
        lastindex = curr;
    }
}

void Main()
{
    var inputString = "1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30";

    foreach(var s in SplitBy(inputString, ',', 10)) Console.WriteLine(s);
}

这是你可以尝试的。



1）拆分字符串，使用 String.Split [ ^ ]。

2）根据事件计数组合数组，例如1到10或11到20等等。

This is what you can try.

1) Split the string on the , using String.Split[^].
2) Combine the array based on the occurrence count for e.g. 1 to 10 or 11 to 20 and so on.

此代码基于以前的解决方案和想法，就像有人需要随时可用的一样。 。;）

This code is based on previous solutions and ideas, just if someone needs a "ready-to-use" one... ;)

public static class StringExtensions
    {
        public static List<string> SplitAtOccurence(this string input, char separator, int occurence)
        {
            var parts = input.Split(separator);
            var partlist = new List<string>();
            var result = new List<string>();
            for (int i = 0; i < parts.Length; i++)
            {
                if (partlist.Count == occurence)
                {
                    result.Add(string.Join(separator.ToString(), partlist));
                    partlist.Clear();
                }
                partlist.Add(parts[i]);
                if (i == parts.Length - 1) result.Add(string.Join(separator.ToString(), partlist)); // if no more parts, add the rest
            }
            return result;
        }
    }

用法（在同一名称空间中）是这样的：

The usage (in the same namespace) is something like this:

"1,2,3,4,5,6,7,8,9,10".SplitAtOccurence(',', 4);

这将返回一个List，其中包含以下项目：1,2,3,4， 5,6,7,8和9,10

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