Question

我的代码中出现错误的原因是什么：

public void SetOperationDropDown() 
{ 
    if(CmbOperations.Items.Count == 0) 
    { 
        //ByDefault the selected text in the cmbOperations will be -SELECT OPERATIONS-. 

        cmbOperations.SelectedItem = "-SELECT OPERATIONS-";  

        //This is for adding four operations with value in operation dropdown  
        cmbOperations.Items.Insert(0, "PrimaryKeyTables");  
        cmbOperations.Items.Insert(1, "NonPrimaryKeyTables");  
        cmbOperations.Items.Insert(2, "ForeignKeyTables");  
        cmbOperations.Items.Insert(3, "NonForeignKeyTables");  
        cmbOperations.Items.Insert(4, "UPPERCASEDTables");  
        cmbOperations.Items.Insert(5, "lowercasedtables");  
    } 
    else 
    { 
        int? cbSelectedValue = null; 

        //OP ERROR SHOWN HERE
            if(!string.IsNullOrEmpty(cmbOperations.SelectedValue))

        cbSelectedValue = convert.toInt32(cmbOperations.SelectedValue); 
    } 

    //load your combo again 

    //OP ERROR SHOWN HERE
    if(cbSelectedValue != null) 

    cmbOperations.SelectedValue = cbSelectedValue.ToString(); 
}

（此代码段中特别出现错误： cbSelectedValue.ToString();）

Answer 1

SelectedValue是一个对象，而不是一个字符串。所以你需要将它转换为字符串：

if(cmbOperations.SelectedValue != null && !cmbOperations.SelectedValue.ToString() == string.Empty)

功能中显示错误

1 个答案: