C# DataTable 在控制台中显示单行

Question

我四处寻找一种方法来显示 C# 数据表的整行，既通过引用行号，也通过简单地将行内容写入字符串变量并在控制台中显示字符串。我可以指定确切的行和字段值并显示该值，但不能显示整行。这不是 C# 中的列表，这是数据表。

对于下面的简单代码，我得到的第一个 WriteLine 的输出是 "Horse"，但是后两个 WriteLine 命令，我得到的是控制台输出 "System.Data.DataRow" 而不是整行数据.

我做错了什么？任何帮助将不胜感激。

using System;
using System.Data;
using System.Threading;

namespace DataTablePractice
{
    class Program
    {
        static void Main(string[] args)
        {

            // Create a DataTable.
            using (DataTable table = new DataTable())
            {
                // Two columns.
                table.TableName = "table";
                table.Columns.Add("Number", typeof(string));
                table.Columns.Add("Pet", typeof(string));

                // ... Add two rows.
                table.Rows.Add("4", "Horse");
                table.Rows.Add("10", "Moose");

                // ... Display first field of the first row in the console
                Console.WriteLine(table.Rows[0].Field<string>(1));

                //...Display the first row of the table in the console
                Console.WriteLine(table.Rows[0]);

                //...Create a new row variable to add a third pet
                var newrow = table.Rows.Add("15", "Snake");
                string NewRowString = newrow.ToString();

                //...Display the new row of data in the console
                Console.WriteLine(NewRowString);

                //...Sleep for a few seconds to examine output
                Thread.Sleep(4000);

            }
        }
    }
}

Answer 1

当你运行这个：

Console.WriteLine(table.Rows[0]);

实际上是这样调用的：

Console.WriteLine(table.Rows[0].ToString());  // prints object type, in this case a DataRow

如果是你自己的class，你可以override ToString to return whatever you need, but you don't have that option with the DataRow class. And so it uses the default behavior as described here:

Default implementations of the Object.ToString method return the fully qualified name of the object's type.

您可以遍历列，例如：

var row = table.Rows[0];
for (var i = 0; i < row.Count; i++)
    Console.Write(row[i] + " : ");

或者，将它们全部打印出来的更短方法：

Console.WriteLine(String.Join(" : ", table.Rows[0].ItemArray));

鉴于您的数据，也许您只想引用这两个字段？

foreach (DataRow row in dt.Rows)
    Console.WriteLine($"You have {row[0]} {row[1]}(s).");

// You have 4 Horse(s).
// You have 10 Moose(s).

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