我的应用中有代码：
ng-options="method.name for selectedHelp.methods in selectedHelp"
但是隐藏了整个选择标记，直到＆＃34; selectedHelp＆＃34;变量被赋值。我怎样才能防止ng-options计算，直到＆＃34; selectedHelp＆＃34;有价值吗？因为否则会引发错误。
答案 0 :(得分：1)
使用class Program
{
static void Main(string[] args)
{
pl a ,b,c;
a= new pl();
b=new pl();
a.mark=99;
b.mark=10;
c = a+b;
if (c != b)
Console.WriteLine("is not equal");
else
Console.WriteLine("both are equal");
Console.WriteLine(c.mark);
Console.ReadLine();
}
}
class pl
{
public int mark;
public static pl operator+ ( pl a , pl b) // 1. here It Work's Perfectly At + overloading
{
pl mm = new pl();
mm.mark = a.mark + b.mark;
return mm;
}
public static bool operator!= (pl m , pl n) // 2. unable to overload
{
if (m.mark != n.mark)
return true;
else
return false;
}
}
隐藏ng-if，直到selectedHelp可用：
ng-options