将字符串列表转换为字节数组

Question

我正在尝试编写一个接受a List<string>然后将整个列表转换为一个大字节数组的方法.像这样:

private byte[] ConvertStringsToBytes(List<string> list)
{
    List<byte> byteList = new List<byte>();

    foreach (var i in list)
    {
        byteList.Add(Encoding.UTF8.GetBytes(i));
    }

    return byteList.ToArray();
}

但是我得到:

参数类型'byte []'不能分配给byteList.Add(Encoding.UTF8.GetBytes(i))上的参数类型'byte';

我哪里错了？如何正确将此列表转换为一个字节数组？

Answer 1

一种更有效的方法是首先将字符串连接在一起然后将其转换为字节数组,如下所示:

List<string> input = new List<string> { "first", "second" };
string fullString = String.Join(String.Empty, list.ToArray());
byte[] byteArray = Encoding.UTF8.GetBytes(fullString);

如果性能很重要并且您在该列表中有很多字符串,那么您希望这样: 编辑:基准测试后,此方法确实比上述方法慢.

List<string> input = new List<string> { "first", "second" };
StringBuilder sb = new StringBuilder();
foreach (string s in input )
    sb.Append(s);

byte[] byteArray = Encoding.UTF8.GetBytes(sb.ToString());

编辑: 对本文中提到的一些方法进行了一些基准测试.以下是发布版本的输出:

ConvertWithString         896ms
ConvertWithStringBuilder  858ms
ConvertWithConcat        1529ms
ConvertWithSelectMany    2234ms
ConvertWithBuffer         904ms

ConvertWithString         501ms
ConvertWithStringBuilder  919ms
ConvertWithConcat        1435ms
ConvertWithSelectMany    2044ms
ConvertWithBuffer         636ms

如果你没有很多字符串,看起来性能并不重要.

这是代码:

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;

namespace ConsoleApplication2
{
    internal class Program
    {
        static byte[] ConvertWithBuffer(List<string> list)
        {
            int totalSize = list.Sum(x => Encoding.UTF8.GetByteCount(x));
            byte[] buffer = new byte[totalSize];

            int ix = 0;

            foreach (string str in list)
                ix += Encoding.UTF8.GetBytes(str, 0, str.Length, buffer, ix);

            return buffer;
        }

        static byte[] ConvertWithConcat(List<string> list) { return Encoding.UTF8.GetBytes(String.Concat(list)); }

        static byte[] ConvertWithSelectMany(List<string> list)
        {
            return list
                .SelectMany(line => Encoding.UTF8.GetBytes(line))
                .ToArray();
        }

        static byte[] ConvertWithString(List<string> input)
        {
            string fullString = String.Join(String.Empty, input.ToArray());
            return Encoding.UTF8.GetBytes(fullString);
        }

        static byte[] ConvertWithStringBuilder(List<string> input)
        {
            StringBuilder sb = new StringBuilder();
            foreach (string s in input)
                sb.Append(s);

            return Encoding.UTF8.GetBytes(sb.ToString());
        }

        static IEnumerable<string> CreateList()
        {
            for (int i = 0; i < 10000000; i++)
                yield return i.ToString();
        }

        static void Main(string[] args)
        {
            List<string> strings = CreateList().ToList();
            Stopwatch stopWatch = Stopwatch.StartNew();

            // warm up
            ConvertWithString(strings);
            ConvertWithStringBuilder(strings);
            ConvertWithConcat(strings);
            ConvertWithSelectMany(strings);
            ConvertWithBuffer(strings);

            // testing

            stopWatch.Restart();
            ConvertWithString(strings);
            Console.WriteLine("ConvertWithString {0}ms", stopWatch.ElapsedMilliseconds);

            stopWatch.Restart();
            ConvertWithStringBuilder(strings);
            Console.WriteLine("ConvertWithStringBuilder {0}ms", stopWatch.ElapsedMilliseconds);

            stopWatch.Restart();
            ConvertWithConcat(strings);
            Console.WriteLine("ConvertWithConcat {0}ms", stopWatch.ElapsedMilliseconds);

            stopWatch.Restart();
            ConvertWithSelectMany(strings);
            Console.WriteLine("ConvertWithSelectMany {0}ms", stopWatch.ElapsedMilliseconds);

            stopWatch.Restart();
            ConvertWithBuffer(strings);
            Console.WriteLine("ConvertWithBuffer {0}ms", stopWatch.ElapsedMilliseconds);

            Console.WriteLine("press any key...");
            Console.ReadKey();
        }
    }
}