我有个一个dt,要取其中一列的值经过判断放到数组中,需要附值的数组我定义成类的全局变量了,但是这段代码报错
错误是未将对象引用或设置为对象示例
请高手帮忙解决,而且我的第2层循环也问题,不知道该怎么解决....for (int k = 0; k < ds.Tables[0].Rows.Count; k++)//循环取出m=0.2时的值
{
mach = double.Parse(ds.Tables[0].Rows[k]["马赫数"].ToString());
if (0.205 > mach && mach > 0.195)
{ count = count + 1;
for (int c = 0; c < count; c++)
{
arr[a] = mach;
}
}
}
for (int j = 0; j < avg.Length ; j++)
{
a += avg[i] / avg.Length;
}
错误是未将对象引用或设置为对象示例
请高手帮忙解决,而且我的第2层循环也问题,不知道该怎么解决....for (int k = 0; k < ds.Tables[0].Rows.Count; k++)//循环取出m=0.2时的值
{
mach = double.Parse(ds.Tables[0].Rows[k]["马赫数"].ToString());
if (0.205 > mach && mach > 0.195)
{ count = count + 1;
for (int c = 0; c < count; c++)
{
arr[a] = mach;
}
}
}
for (int j = 0; j < avg.Length ; j++)
{
a += avg[i] / avg.Length;
}
List<double> list = new List<double>();
for (int k = 0; k < ds.Tables[0].Rows.Count; k++)
{
double mach = Convert.ToDouble(ds.Tables[0].Rows[k]["马赫数"]);
if(mach < 0.205 && mach > 0.195)
{
list.Add(mach);
}
}
arr = list.ToArray();
List list = new List();
for (int k = 0; k < ds.Tables[0].Rows.Count; k++)
{
double mach = Convert.ToDouble(ds.Tables[0].Rows[k]["马赫数"]);
if(mach < 0.205 && mach > 0.195)
{
list.Add(mach);
}
}
arr = list.ToArray();
List<double> list = new List<double>();
for (int k = 0; k < ds.Tables[0].Rows.Count; k++)
{
double mach = Convert.ToDouble(ds.Tables[0].Rows[k]["马赫数"]);
if(mach < 0.205 && mach > 0.195)
{
list.Add(mach);
}
}
arr = list.ToArray();
for (int k = 0; k < ds.Tables[0].Rows.Count; k++)
{
double mach = 0;
if (double.TryParse(ds.Tables[0].Rows[k]["马赫数"].ToString(),out mach) && mach < 0.205 && mach > 0.195)
{
list.Add(mach);
}
}double[] arr = list.ToArray();你的第二个循环干嘛?求平均值么?
直接用DataTable.Compute方法就可以了~~~
DataTable table = new DataTable();
table.Columns.Add("count", typeof(int));for (int i = 0; i < 5; i++)
{
DataRow row = table.NewRow();
row["count"] = i;
table.Rows.Add(row);
}double result = 0;
double.TryParse(table.Compute("AVG(count)", "count > 3").ToString(), out result);