Error including sum of values in the footer of a gridview

Question

I’m trying to include in the footnote of a gridview the sum of two columns, but I’m having difficulty creating the method that performs this function.

I’ve already put the property ShowFooter as true, now I have to implement the event DataBound but it’s not working. Someone can help me?

 protected void gvcarteira_DataBound(object sender, EventArgs e)
    {
                    double val1 = 0;
        double val2 = 0;
       // foreach (GridViewRow row in gvcarteira.Rows)

        for (int i; gvcarteira.Rows.Count - 1; i++)
        {
            // converte o preco e a qtde para multiplicar e somar no total         

            double qt = double.Parse(gvcarteira.Rows[i].Cells[3].Text);
            double qtd = double.Parse(gvcarteira.Rows[i].Cells[4].Text);


            val1 = val1 + qt;
            val2 = val2 + qtd;


        }
        gvcarteira.FooterRow.Cells[0].Text = "Valor das Ações";
        gvcarteira.FooterRow.Cells[1].Text = val1.ToString();

        gvcarteira.FooterRow.Cells[3].Text = "Valor Gasto";
        gvcarteira.FooterRow.Cells[4].Text = val2.ToString();
      }

I want it to look something like this:

Answer 1

Example:

Gridview:

<asp:GridView ID="GridDados" AutoGenerateColumns="False" runat="server" ItemType="WebAppDiegoWebForms.Fulano" OnRowDataBound="GridDados_RowDataBound" ShowFooter="True">
    <Columns>
        <asp:BoundField DataField="Codigo" HeaderText="Código" DataFormatString="{0:0000}"/>
        <asp:BoundField DataField="Nome" HeaderText="Nome" />
        <asp:BoundField DataField="Data" DataFormatString="{0:d}" HeaderText="Data" />
        <asp:BoundField DataField="Quantidade" HeaderText="Quantidade" />
        <asp:BoundField DataField="Valor" DataFormatString="{0:N2}" HeaderText="Valor" />
        <asp:BoundField DataField="ValorParcial" DataFormatString="{0:N2}" HeaderText="Valor Parcial" />
    </Columns>
</asp:GridView>

In his Griddados has the columns Amount, Valor and Partial value and in the Footer will be summing all values of Partial value.

Like:

Class model:

public class Fulano
{
    public int Codigo { get; set; }
    public string Nome { get; set; }
    public DateTime Data { get; set; }
    public Decimal Valor { get; set; }
    public int Quantidade { get; set; }
}

Code of this Webform

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        var valores = (new Fulano[] 
        {
            new Fulano { Codigo = 1,  Nome = "Fulano 1", Data = DateTime.Now, Valor = 100M, Quantidade = 2},
            new Fulano { Codigo = 2, Nome = "Fulano 2", Data = DateTime.Now, Valor = 200M, Quantidade = 1},
            new Fulano { Codigo = 3, Nome = "Fulano 3", Data = DateTime.Now, Valor = 100M, Quantidade = 1},
            new Fulano { Codigo = 4, Nome = "Fulano 4", Data = DateTime.Now, Valor = 150M, Quantidade = 1},
            new Fulano { Codigo = 5, Nome = "Fulano 5", Data = DateTime.Now, Valor = 300M, Quantidade = 1}
        })
        .Select(x => new
        {
            x.Codigo,
            x.Nome,
            x.Data,
            x.Valor,
            x.Quantidade,
            ValorParcial = (x.Valor * x.Quantidade)
        })
        .ToArray();

        GridDados.DataSource = valores;
        GridDados.DataBind();
    }
}

private decimal total = 0;
private decimal valor = 0;        
protected void GridDados_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        valor = 0;               
        if (decimal.TryParse(e.Row.Cells[5].Text, out valor)){
            total += valor;
        }

    } else if (e.Row.RowType == DataControlRowType.Footer)
    {
        e.Row.Cells[4].Text = "Total:";
        e.Row.Cells[5].Text = total.ToString("N2");
        total = 0;
    }            
}

Loading in this example is manual, but you can use it in your own way. The only pecularity that before sending to GridView Griddados I do a multiplication ValorParcial = (x.Valor * x.Quantidade) and send the data to grid all formatted.

In the GridDados_RowDataBound i do the proper sum operations and at the end I show in the Footer of Gridview. OBS: the variables of type decimal total and value are placed outside the method GridDados_RowDataBound.

Upshot:

Answer 2

The problem is not the footer itself. It is the loop iteration. Consider changing the for by a foreach, which is safer:

foreach (GridViewRow linha in gvcarteira.Rows)
{
    // converte o preco e a qtde para multiplicar e somar no total         

    double qt = double.Parse(linha.Cells[3].Text);
    double qtd = double.Parse(linha.Cells[4].Text);

    val1 = val1 + qt;
    val2 = val2 + qtd;

}