为什么三元运算符显示错误? [英] Why ternary operator showing error ?

问题描述

dr[columnname] = datavalue.Trim() == "" ? DBNull.Value : Convert.ToInt32(datavalue);

什么是正确的编码?

如果datavalue.Trim()=="，那么我想将空格传递到我的列dr [columnname].

what is the correct coding?

if datavalue.Trim() == "" then i want to pass the blank space to my column dr[columnname].

推荐答案

您正在尝试:

请参见以下代码:

You are tring impossible:

See the below code:

DataTable table = new DataTable();
            Nullable<int> X = 10;
            X = null;
            table.Columns.Add("Dosage", X.GetType() );
            string datavalue = "123";
            DataRow row = table.NewRow();
            row["Dosage"] = datavalue.Trim() == "" ? 0 : Convert.ToInt32(datavalue);

在此值中使用0而不是0，如果您尝试使用null或DBNull或应用程序无法正常运行的任何内容，则应考虑使用0代替

In this instead of 0, if you try null or DBNull or anything your application will not work, you should considering 0 instead

您正在表达式中混合类型，

You are mixing types in your expression, DBNull.Value[^] is not an Int32.

尝试一下，

Try this,

dr[columnname] = datavalue.Trim() == "" ? String.Empty : Convert.ToInt32(datavalue).ToString();

或

Or

dr[columnname] = datavalue.Trim() == "" ? (int?)null : Convert.ToInt32(datavalue);

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