Question

我创建了一个多维数组：

 string[,] array_questions = new string[dt.Rows.Count, dt.Columns.Count]; 
    for (i = 0; i < dt.Rows.Count; i++)
   {
   for (j = 0; j < dt.Columns.Count; j++)
   {
       array_questions[i, j] = dt.Rows[i][j].ToString();
       //Response.Write(array_questions[i, j]);
  }
 //  Response.Write(Environment.NewLine);
 //Response.Write("\n");
  }
foreach (string number in array_questions)
    {
        //Response.Write(number + " ");
        //Response.Write(Environment.NewLine);
        Response.Write(string.Join(", ", number) + Environment.NewLine);         
    }

但它显示如下错误：错误1'string.Join（string，string []）'的最佳重载方法匹配有一些无效的参数..请帮忙

Answer 1

您不需要for循环来加入字符串。

string.Join(", ", array_questions)

替换代码

foreach (string number in array_questions)
{
    //Response.Write(number + " ");
    //Response.Write(Environment.NewLine);
    Response.Write(string.Join(", ", number) + Environment.NewLine);         
}

与

Response.Write(string.Join(", ", array_questions) + Environment.NewLine);

Answer 2

您需要展平数组才能使用string.Join。它需要分隔符和一维数组，所以你可能需要做这样的事情。但不确定你想在这里实现什么。您正尝试将string.Join(string, string[])称为string.Join(string, string)

尝试这样的事情：

        var sdArray= new List<string>();
        for (var i = 0; i < dt.Rows.Count; i++) //Get the length of first Dimension
        {
            for (var j = 0; j < dt.Columns.Count; j++) //Get the length of second Dimension
            {
                sdArray.Add(array_questions[i, j]);
            }
        }

       ///
        Response.Write(string.Join(", ", sdArray) + Environment.NewLine);

使用Linq，您可以更好地平整这一点。

像这样的东西

  string joinedSetOfQns= string.Join(",", 
       Enumerable.Range(0, dt.Rows.Count)
        .SelectMany(i => Enumerable.Range(0, dt.Columns.Count)
        .Select(j => array_questions[i, j])));    

               Response.Write(joinedSetOfQns + Environment.NewLine);

这是string.Join

的辩护

public static string Join(
    string separator,
    params string[] value  /// <-- Takes single Dimensional Array not a string.
)

更新：因为您需要加入Rowwise

        for (var i = 0; i < dt.Rows.Count; i++)
        {
            var result = new List<string>();
            for (var j = 0; j < dt.Columns.Count; j++)
            {
                result.Add(array_questions[i, j]);
            }
           Response.Write(string.Join(", ", result) + Environment.NewLine);
        }

创建多维数组时string.join出错

2 个答案:

更新：因为您需要加入Rowwise