Write for loop with same function as foreach

Question

I have my foreach loop:

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++;
}

I wanna do the same but in a for loop instead. Tried this (don't work because it can't find data (obviously):

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);
}

How can I re-write my for loop so it matches my foreach loop?

Wait, what? You're using a foreach over the Rows so that you could take the table and then iterate over its rows using an indexer? Why aren't you simply doing data["Date"] etc. in your foreach code? — Luaan
– Luaan, Commented Mar 31, 2014 at 7:45
Also, note that you have to create a new instance of calc in each iteration of the loop (unless it's a struct), otherwise you'll have a nice list of completely identical values in cList. And of course, there's no reason to convert the value to string and then to a given data type - you can cast it right away, eg. (decimal)row["Capital balance"]. — Luaan
– Luaan, Commented Mar 31, 2014 at 7:50
@Luaan When I use data["Date"] I get "Input string was not a correct format". So that doesn't work for me — MrProgram
– MrProgram, Commented Mar 31, 2014 at 8:14
Well, for a date, you'd obviously have to use (DateTime)data["Date"]. Assuming you do actually have a structure in the data table. If it's all made of strings, you're going to have to do the parsing (but you still should do a cast, rather than ToString). — Luaan
– Luaan, Commented Mar 31, 2014 at 8:17

Sudhakar Tillapudi · Accepted Answer · 2014-03-31 07:46:49Z

You need to get the DataRow for each iteration .

Add the following statement in forloop as first statement:

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

Complete Code:

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);
}

Sriram Sakthivel · Accepted Answer · 2014-03-31 07:48:40Z

1

In first place you're using foreach itself wrong. You already have DataRow and still you're having a counter, etc etc they are not required.

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   
}

answered Mar 31, 2014 at 7:48

Sriram Sakthivel

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Comments

Luaan · Accepted Answer · 2014-03-31 07:46:58Z

0

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);
}

Or, of course, you can simply use LINQ:

var cList = 
  result.Tables[0].Rows.Select
  (
    (row, index) =>
    {
      var calc = new YourCalc();

      calc.Something = row["SomeField"] as SomeType;

      return calc;
    }
  ).ToList();

answered Mar 31, 2014 at 7:46

Luaan

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