你如何在 C# 中用 2 个字符计数拆分字符串？

Question

I know how to do a string split if there's a letter, number, that I want to replace.

But how could I do a string.Split() by 2 char counts without replacing any existing letters, number, etc...?

Example:

string MAC = "00122345"

I want that string to output: 00:12:23:45

Answer 1

You could create a LINQ extension method to give you an IEnumerable<string> of parts:

public static class Extensions
{
    public static IEnumerable<string> SplitNthParts(this string source, int partSize)
    {
        if (string.IsNullOrEmpty(source))
        {
            throw new ArgumentException("String cannot be null or empty.", nameof(source));
        }

        if (partSize < 1)
        {
            throw new ArgumentException("Part size has to be greater than zero.", nameof(partSize));
        }

        return Enumerable
            .Range(0, (source.Length + partSize - 1) / partSize)
            .Select(pos => source
                .Substring(pos * partSize, 
                    Math.Min(partSize, source.Length - pos * partSize)));
    }
}

Usage:

var strings = new string[] { 
    "00122345", 
    "001223453" 
};

foreach (var str in strings)
{
    Console.WriteLine(string.Join(":", str.SplitNthParts(2)));
}
// 00:12:23:45
// 00:12:23:45:3

Explanation:

• Use Enumerable.Range to get number of positions to slice string. In this case its the length of the string + chunk size - 1 , since we need to get a big enough range to also fit leftover chunk sizes.
• Enumerable.Select each position of slicing and get the startIndex using String.Substring using the position multiplied by 2 to move down the string every 2 characters. You will have to use Math.Min to calculate the smallest size leftover size if the string doesn't have enough characters to fit another chunk. You can calculate this by the length of the string - current position * chunk size .
• String.Join the final result with ":" .

You could also replace the LINQ query with yield here to increase performance for larger strings since all the substrings won't be stored in memory at once:

for (var pos = 0; pos < source.Length; pos += partSize)
{
    yield return source.Substring(pos, Math.Min(partSize, source.Length - pos));
}

Answer 2

You can use something like this:

string newStr= System.Text.RegularExpressions.Regex.Replace(MAC, ".{2}", "$0:");

To trim the last colon, you can use something like this.

    newStr.TrimEnd(':');

Microsoft Document

Answer 3

Try this way.

    string MAC = "00122345";
    MAC = System.Text.RegularExpressions.Regex.Replace(MAC,".{2}", "$0:");
    MAC = MAC.Substring(0,MAC.Length-1);
    Console.WriteLine(MAC);

Answer 4

An easy to understand and simple solution.

This is a simple fast modified answer in which you can easily change the split char .

• This answer also checks if the number is even or odd , to make the suitable string.Split() .

---

input : 00122345

output : 00:12:23:45

---

input : 0012234

output : 00:12:23:4

---

//The List that keeps the pairs
List<string> MACList = new List<string>();

//Split the even number into pairs
for (int i = 1; i <= MAC.Length; i++)
{               
    if (i % 2 == 0)
    {
        MACList.Add(MAC.Substring(i - 2, 2));
    }
}

//Make the preferable output
string output = "";
for (int j = 0; j < MACList.Count; j++)
{
    output = output + MACList[j] + ":";
}

//Checks if the input string is even number or odd number
if (MAC.Length % 2 == 0)
{
    output = output.Trim(output.Last());
}
else
{
    output += MAC.Last();
}

//input : 00122345
//output : 00:12:23:45

//input : 0012234
//output : 00:12:23:4

Answer 5

A quite fast solution, 8-10x faster than the current accepted answer (regex solution) and 3-4x faster than the LINQ solution

public static string Format(this string s, string separator, int length)
{
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < s.Length; i += length)
    {
        sb.Append(s.Substring(i, Math.Min(s.Length - i, length)));
        if (i < s.Length - length)
        {
            sb.Append(separator);
        }
    }

    return sb.ToString();
}

Usage:

string result = "12345678".Format(":", 2);

Answer 6

这是使用LINQ Enumerable.Aggregate的一 (1) 行替代方法。

string result = MAC.Aggregate("", (acc, c) => acc.Length % 3 == 0 ? acc += c : acc += c + ":").TrimEnd(':');