运算符+ =不能应用于类型为object和object的操作数 [英] operator += cannot be applied to operands of type object and object

问题描述

亲爱的所有

我对此编码有点问题

Dear all

i have problem with this bit of coding

dr["DataColumn1"] += dtshort.Rows[0][0];

当我将值传递给dtshort.Rows [0] [0] = 1时，它将很好地存储dr ["DataColumn1"]，但是我的问题是当我使用循环时，我想向dr ["DataColumn1"]连续添加值br/>
如何做到这一点，...

when i pass value to dtshort.Rows[0][0]=1, it ll store dr["DataColumn1"] it fine but my prob is when i am using loop i want continuously add value to dr["DataColumn1"]

How to do this,...

推荐答案

1.实际上，使用DataReader 从数据源获取的值是boxed 对象，它们应unboxed 为其原始类型，如下例所示:

1. The values get from the data source by using DataReader are in fact boxed objects and they should be unboxed to their original types like in the next example:

string name = (string)dr["DataColumn1"];
double number = (double)dr["DataColumn2"];

2.有关boxing 和unboxing的更多详细信息，请参见MSDN: http://msdn.microsoft .com/en-us/library/yz2be5wk.aspx [

2.For more details about boxing and unboxing see in MSDN:http://msdn.microsoft.com/en-us/library/yz2be5wk.aspx[^]

dr [" DataColumn1]可以处理不同类型的数据，以将其类型设置为object(毕竟所有都是对象) .
但是对象不能实现+ =的运算符，因为这是一个普通类型，并且+ =运算符对于不同的实际类型(想象中的1 + 1和``1''+''1'')可能会大不相同...
您可以做的是将dr ["DataColumn1"]转换为它的预期类型，然后应用+ =运算符:

dr["DataColumn1"] can handle different types of data, to do that its type set to object (after all everything is an object).
However object do not implement the operator of += as this is a common type and += operator can be very different for different actual types (imagine 1+1 and ''1''+''1'')...
What you can do is convert dr["DataColumn1"] to it''s expected type and than apply += operator:

int n = Convert.ToInt32(dr["DataColumn1"]);
dr["DataColumn1"] = n + Convert.ToInt32(dtshort.Rows[0][0]);

这篇关于运算符+ =不能应用于类型为object和object的操作数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！