Question

如何将值作为文本而不是void返回？

示例：

private void button1_Click(object sender, EventArgs e)
{
    label1.Text = myvoid("foo", true);
    //Error, Cannot imlicity convert type void to string
}

public void myvoid(string key , bool data)
{
    if (data == true)
    {
        string a = key + " = true";
        MessageBox.Show(a); //How to export this value to labe1.Text?
    }
    else
    {
        string a = key + " = false";
        MessageBox.Show(a); //How to export this value to labe1.Text?
    }
}

如何从返回void的方法中指定值a，而不是显示消息框，并将其应用于label1.Text？

Answer 1

public string myvoid(string key, bool data)
{
    return key + " = " + data;
}

此外，您的方法不应再被称为myvoid，因为它实际上会返回一个值。像FormatValue这样的东西会更好。

Answer 2

private void button1_Click(object sender, EventArgs e)
{
    label1.Text = myvoid("foo", true);
}

public string myvoid(string key , bool data)
{
    if (data)       
        return key + " = true";         
    else       
        return  key + " = false"; 
}

评论中提到的Austin，这将更加干净

public string myvoid(string key , bool data)
{
   return string.Format("{0} = {1}", key, data);
}

Answer 3

将返回类型更改为字符串

 public string myvoid(string key , bool data)
 {
    string a = string.Empty;
    if (data == true)
    {
        a = key + " = true";
        MessageBox.Show(a);//How to export this value to labe1.Text
    }
    else
    {
        a = key + " = false";
        MessageBox.Show(a);//How to export this value to labe1.Text
    }
   return a;
 }

Answer 4

您必须将方法的返回类型更改为字符串

像这样：public string myvoid(string key , bool data)

然后返回字符串a;

像这样：

return a;

Answer 5

查看http://msdn.microsoft.com/en-us/library/t3c3bfhx(v=vs.80).aspx。

如果您真的想使用void，可以使用out谓词。

Answer 6

使用字符串返回类型

private void button1_Click(object sender, EventArgs e)      
    {      
        label1.Text = myvoid("foo", true);   
    } 

public string myvoid(string key , bool data) 
 { 
    string a = string.Empty; 
    if (data == true) 
    { 
        a = key + " = true"; 
        MessageBox.Show(a);
    } 
    else 
    { 
        a = key + " = false"; 
        MessageBox.Show(a);
    } 
   return a; 
 }

如果你坚持虚空，你就可以做到这一点

 private void button1_Click(object sender, EventArgs e)      
    {      
       myvoid("foo", true , label1);   
    } 

    public void myvoid(string key , bool data, label lb) 
     { 
        string a = string.Empty; 
        if (data == true) 
        {   
            a = key + " = true"; 
            MessageBox.Show(a);
        } 
        else 
        { 
            a = key + " = false"; 
            MessageBox.Show(a);
        } 

       lb.Text = a;

     }

如何从方法返回一个字符串

6 个答案: