ArrayExtensionMethods.cs

using System.Collections.Generic;
using System.Text;

namespace Kogane
{
    /// <summary>
    /// 配列の拡張メソッド
    /// </summary>
    public static class ArrayExtensionMethods
    {
        //================================================================================
        // 関数(static)
        //================================================================================
        /// <summary>
        /// 二次元配列のように扱っている一次元配列を文字列に変換して返します
        /// </summary>
        public static string JoinToString<T>
        (
            this IReadOnlyList<T> self,
            int                   column,
            int                   row
        )
        {
            return self.JoinToString
            (
                column: column,
                row: row,
                separator: string.Empty
            );
        }

        /// <summary>
        /// 二次元配列のように扱っている一次元配列を文字列に変換して返します
        /// </summary>
        public static string JoinToString<T>
        (
            this IReadOnlyList<T> self,
            int                   column,
            int                   row,
            string                separator
        )
        {
            var stringBuilder = new StringBuilder();

            for ( var y = 0; y < row; y++ )
            {
                for ( var x = 0; x < column; x++ )
                {
                    stringBuilder.Append( self[ x + y * column ] );

                    if ( x < column - 1 )
                    {
                        stringBuilder.Append( separator );
                    }
                }

                if ( y < row - 1 )
                {
                    stringBuilder.AppendLine();
                }
            }

            return stringBuilder.ToString();
        }
    }
}