代码增加了IEnumerable [英] Code for adding to IEnumerable

问题描述

我有这样一个枚举

IEnumerable<System.Windows.Documents.FixedPage> page;

我如何添加一个页面（例如：D：\\\
ewfile.txt）呢？我曾尝试添加，追加，的毗连等，但没有为我工作。

How can I add a page (eg: D:\newfile.txt) to it? I have tried Add, Append, Concat etc But nothing worked for me.

推荐答案

是，有可能

是可能的串联在一起序列（IEnumerables）和连接后的结果分配给一个新的序列。 （您不能改变原来的顺序。）

It is possible to concatenate sequences (IEnumerables) together and assign the concatenated result to a new sequence. (You cannot change the original sequence.)

内置的 Enumerable.Concat（） 只会串连另一个序列;然而，很容易编写一个扩展方法，可以让您连接一个标量序列

The built-in Enumerable.Concat() will only concatenate another sequence; however, it is easy to write an extension method that will let you concatenate a scalar to a sequence.

下面的代码演示：

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

namespace Demo
{
    public class Program
    {
        [STAThread]
        private static void Main()
        {
            var stringList = new List<string> {"One", "Two", "Three"};

            IEnumerable<string> originalSequence = stringList;

            var newSequence = originalSequence.Concat("Four");

            foreach (var text in newSequence)
            {
                Console.WriteLine(text); // Prints "One" "Two" "Three" "Four".
            }
        }
    }

    public static class EnumerableExt
    {
        /// <summary>Concatenates a scalar to a sequence.</summary>
        /// <typeparam name="T">The type of elements in the sequence.</typeparam>
        /// <param name="sequence">a sequence.</param>
        /// <param name="item">The scalar item to concatenate to the sequence.</param>
        /// <returns>A sequence which has the specified item appended to it.</returns>
        /// <remarks>
        /// The standard .Net IEnumerable extensions includes a Concat() operator which concatenates a sequence to another sequence.
        /// However, it does not allow you to concat a scalar to a sequence. This operator provides that ability.
        /// </remarks>

        public static IEnumerable<T> Concat<T>(this IEnumerable<T> sequence, T item)
        {
            return sequence.Concat(new[] { item });
        }
    }
}

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