编写 for 循环，具有与 foreach 相同的功能

本文关键字：foreach 功能 for 循环 编写 | 更新日期: 2023-09-27 17:55:46

我有我的foreach循环：

var i = 0;
foreach (DataRow data in result.Tables[0].Rows)
{
     var periodStartDate = Convert.ToDateTime(data.Table.Rows[i]["Date"].ToString().Remove(10));
     var periodEndDate = Convert.ToDateTime(data.Table.Rows[i]["Date"].ToString().Remove(0, 12));
     calc.PeriodStartDate = periodStartDate;
     calc.PeriodEndDate = periodEndDate;
     calc.InvoiceAmount = Convert.ToDecimal(data.Table.Rows[i]["Invoice amount"].ToString());
     calc.InterestRate = Convert.ToDecimal(data.Table.Rows[i]["Interest rate"].ToString());
     calc.InterestAmount = Convert.ToDecimal(data.Table.Rows[i]["Interest amount"].ToString());
     calc.Amortization = Convert.ToDecimal(data.Table.Rows[i]["Amortization"].ToString());
     calc.PresentValue = Convert.ToDecimal(data.Table.Rows[i]["Capital balance"].ToString());
     calc.StartValue = Convert.ToDecimal(data.Table.Rows[0]["Capital balance"].ToString());
     cList.Add(calc);
     i++;
}

我想做同样的事情，但改为在 for 循环中。试过这个（不起作用，因为它找不到数据（显然）：

for (int i = 0; i < result.Tables[0].Rows.Count; i++)
{
     var periodStartDate = Convert.ToDateTime(data.Table.Rows[i]["Date"].ToString().Remove(10));
     var periodEndDate = Convert.ToDateTime(data.Table.Rows[i]["Date"].ToString().Remove(0, 12));
     calc.PeriodStartDate = periodStartDate;
     calc.PeriodEndDate = periodEndDate;
     calc.InvoiceAmount = Convert.ToDecimal(data.Table.Rows[i]["Invoice amount"].ToString());
     calc.InterestRate = Convert.ToDecimal(data.Table.Rows[i]["Interest rate"].ToString());
     calc.InterestAmount = Convert.ToDecimal(data.Table.Rows[i]["Interest amount"].ToString());
     calc.Amortization = Convert.ToDecimal(data.Table.Rows[i]["Amortization"].ToString());
     calc.PresentValue = Convert.ToDecimal(data.Table.Rows[i]["Capital balance"].ToString());
     calc.StartValue = Convert.ToDecimal(data.Table.Rows[0]["Capital balance"].ToString());
     cList.Add(calc);
}

如何重写我的 for 循环，使其与我的 foreach 循环匹配？

编写 for 循环，具有与 foreach 相同的功能

您需要获取每次迭代的数据行。

在 forloop 中添加以下语句作为第一个语句：

DataRow data = result.Tables[0].Rows[i];

完整代码：

for (int i = 0; i < result.Tables[0].Rows.Count; i++)
{
     DataRow data = result.Tables[0].Rows[i];
     var periodStartDate = Convert.ToDateTime(data.Table.Rows[i]["Date"].ToString().Remove(10));
     var periodEndDate = Convert.ToDateTime(data.Table.Rows[i]["Date"].ToString().Remove(0, 12));
     calc.PeriodStartDate = periodStartDate;
     calc.PeriodEndDate = periodEndDate;
     calc.InvoiceAmount = Convert.ToDecimal(data.Table.Rows[i]["Invoice amount"].ToString());
     calc.InterestRate = Convert.ToDecimal(data.Table.Rows[i]["Interest rate"].ToString());
     calc.InterestAmount = Convert.ToDecimal(data.Table.Rows[i]["Interest amount"].ToString());
     calc.Amortization = Convert.ToDecimal(data.Table.Rows[i]["Amortization"].ToString());
     calc.PresentValue = Convert.ToDecimal(data.Table.Rows[i]["Capital balance"].ToString());
     calc.StartValue = Convert.ToDecimal(data.Table.Rows[0]["Capital balance"].ToString());
     cList.Add(calc);
}
首先，

你用错了foreach本身。您已经有DataRow，但仍然有一个计数器等，它们不是必需的。

foreach (DataRow data in result.Tables[0].Rows)
{
     var periodStartDate = Convert.ToDateTime(data["Date"].ToString().Remove(10));
     //You can simplify rest like this with `data`
}
for (int i = 0; i < result.Tables[0].Rows.Count; i++)
{    
    DataRow data = result.Tables[0].Rows[i];
    var periodStartDate = Convert.ToDateTime(data["Date"].ToString().Remove(10)); 
    //And so on   
}

var table = result.Tables[0];
for (int i = 0; i < table.Rows.Count; i++)
{
     var periodStartDate = Convert.ToDateTime(table.Rows[i]["Date"].ToString()
                                  .Remove(10));
     var periodEndDate   = Convert.ToDateTime(table.Rows[i]["Date"].ToString()
                                  .Remove(0, 12));
     // And the rest of the fields...
     cList.Add(calc);
}

或者，当然，您可以简单地使用 LINQ：

var cList = 
  result.Tables[0].Rows.Select
  (
    (row, index) =>
    {
      var calc = new YourCalc();
      calc.Something = row["SomeField"] as SomeType;
      return calc;
    }
  ).ToList();
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