no overload for method “ToString” takes 1 arguments

匿名 (未验证) 提交于 2019-12-03 01:44:01

问题:

I have a data reader to read the datas from database. I am reading TotalPrice from sales table. I would like to show the total price as 2 decimal place.

The code is something link that:

TotalPrice.Text = myReader["TotalPrice"].ToString("N2"); 

However i encounted this error: no overload for method "ToString" takes 1 arguments What's wrong with the code?

回答1:

Assuming that TotalPrice is a Decimal column, and that myReader is a DataReader:

TotalPrice.Text = myReader.GetDecimal(myReader.GetOrdinal("TotalPrice")).ToString("N2"); 

The idea here is that myReader's indexer (what you are using when you call myReader["TotalPrice"]) returns an Object. It has to, since it doesn't know at compile time what type the column is. By using .GetDecimal(), you are assuring that you get a Decimal value back, or an error.

The .ToString overload that takes a format string is declared on Decimal, not on Object. Object's .ToString takes no arguments.

The inner call to GetOrdinal returns the field's index given the name- if you are doing this in a loop for multiple data rows, you'd probably want to cache that in a variable.



回答2:

String.Format() will do the trick. F2 is fixed-point notation with 2 decimal places.

TotalPrice.Text = string.Format("{0:F2}", (double)myReader["TotalPrice"]); 


标签
易学教程内所有资源均来自网络或用户发布的内容,如有违反法律规定的内容欢迎反馈
该文章没有解决你所遇到的问题?点击提问,说说你的问题,让更多的人一起探讨吧!