我想知道的是如何将字符串转换为运算符。
我希望能够将一个值与另一个值进行比较，并且它是否为真的条件是字符串。例如，字符串可能是'＆gt;'或'＆gt; ='或其他我可以定义为'GREATER_THAN'的东西。
最佳方式只是一个案例，还是有更好的使用C＃的wizadry？
答案 0 :(得分：6)
您可以使用以下简单方法：
private bool Compare(string operator, int x, int y)
{
switch (operator)
{
case ">": return x > y;
case "<": return x < y;
case "==": return x == y;
... etc.
}
}
bool result = Compare(">", 6, 8);
答案 1 :(得分：3)
这样的事情（让我们概括一下解决方案）：
ini_set('display_errors', 1);
foreach ($showAll as $client)
{
$data_array[] = array(
'name' => $client['name'],
'value' => $client['name'],
'text' => $client['name']
);
}
// add these lines to your code.
$result=array();
$result["success"]=true;
$result["results"]=$data_array;
echo json_encode($result);
样品：
private static bool MyCompare<T>(string comparer, T x, T y) where T: IComparable<T> {
// we can't put x.CompareTo(y) since either x or y or both can be null
int v = Comparer<T>.Default.Compare(x, y);
//TODO: you may want strict tests: if (comparer == ">") return v == 0; else if () ...
if (comparer.Contains('<') && v < 0)
return true;
if (comparer.Contains('>') && v > 0)
return true;
if (comparer.Contains('=') && v == 0)
return true;
if (comparer.Contains('!') && v != 0)
return true;
return false;
}
答案 2 :(得分：-1)
不能定义新的运算符，但是如果要为自己的新业务对象定义比较，则可以为模型的用户运算符重载。 在这里找到如何做到这一点
https://www.tutorialspoint.com/csharp/csharp_operator_overloading.htm
using System;
namespace OperatorOvlApplication
{
class Box
{
private double length; // Length of a box
private double breadth; // Breadth of a box
private double height; // Height of a box
public double getVolume()
{
return length * breadth * height;
}
public void setLength( double len )
{
length = len;
}
public void setBreadth( double bre )
{
breadth = bre;
}
public void setHeight( double hei )
{
height = hei;
}
// Overload + operator to add two Box objects.
public static Box operator+ (Box b, Box c)
{
Box box = new Box();
box.length = b.length + c.length;
box.breadth = b.breadth + c.breadth;
box.height = b.height + c.height;
return box;
}
public static bool operator == (Box lhs, Box rhs)
{
bool status = false;
if (lhs.length == rhs.length && lhs.height == rhs.height && lhs.breadth == rhs.breadth)
{
status = true;
}
return status;
}
public static bool operator !=(Box lhs, Box rhs)
{
bool status = false;
if (lhs.length != rhs.length || lhs.height != rhs.height || lhs.breadth != rhs.breadth)
{
status = true;
}
return status;
}
public static bool operator <(Box lhs, Box rhs)
{
bool status = false;
if (lhs.length < rhs.length && lhs.height < rhs.height && lhs.breadth < rhs.breadth)
{
status = true;
}
return status;
}
public static bool operator >(Box lhs, Box rhs)
{
bool status = false;
if (lhs.length > rhs.length && lhs.height > rhs.height && lhs.breadth > rhs.breadth)
{
status = true;
}
return status;
}
public static bool operator <=(Box lhs, Box rhs)
{
bool status = false;
if (lhs.length <= rhs.length && lhs.height <= rhs.height && lhs.breadth <= rhs.breadth)
{
status = true;
}
return status;
}
public static bool operator >=(Box lhs, Box rhs)
{
bool status = false;
if (lhs.length >= rhs.length && lhs.height >= rhs.height && lhs.breadth >= rhs.breadth)
{
status = true;
}
return status;
}
public override string ToString()
{
return String.Format("({0}, {1}, {2})", length, breadth, height);
}
}
class Tester
{
static void Main(string[] args)
{
Box Box1 = new Box(); // Declare Box1 of type Box
Box Box2 = new Box(); // Declare Box2 of type Box
Box Box3 = new Box(); // Declare Box3 of type Box
Box Box4 = new Box();
double volume = 0.0; // Store the volume of a box here
// box 1 specification
Box1.setLength(6.0);
Box1.setBreadth(7.0);
Box1.setHeight(5.0);
// box 2 specification
Box2.setLength(12.0);
Box2.setBreadth(13.0);
Box2.setHeight(10.0);
//displaying the Boxes using the overloaded ToString():
Console.WriteLine("Box 1: {0}", Box1.ToString());
Console.WriteLine("Box 2: {0}", Box2.ToString());
// volume of box 1
volume = Box1.getVolume();
Console.WriteLine("Volume of Box1 : {0}", volume);
// volume of box 2
volume = Box2.getVolume();
Console.WriteLine("Volume of Box2 : {0}", volume);
// Add two object as follows:
Box3 = Box1 + Box2;
Console.WriteLine("Box 3: {0}", Box3.ToString());
// volume of box 3
volume = Box3.getVolume();
Console.WriteLine("Volume of Box3 : {0}", volume);
//comparing the boxes
if (Box1 > Box2)
Console.WriteLine("Box1 is greater than Box2");
else
Console.WriteLine("Box1 is greater than Box2");
if (Box1 < Box2)
Console.WriteLine("Box1 is less than Box2");
else
Console.WriteLine("Box1 is not less than Box2");
if (Box1 >= Box2)
Console.WriteLine("Box1 is greater or equal to Box2");
else
Console.WriteLine("Box1 is not greater or equal to Box2");
if (Box1 <= Box2)
Console.WriteLine("Box1 is less or equal to Box2");
else
Console.WriteLine("Box1 is not less or equal to Box2");
if (Box1 != Box2)
Console.WriteLine("Box1 is not equal to Box2");
else
Console.WriteLine("Box1 is not greater or equal to Box2");
Box4 = Box3;
if (Box3 == Box4)
Console.WriteLine("Box3 is equal to Box4");
else
Console.WriteLine("Box3 is not equal to Box4");
Console.ReadKey();
}
}
}
否则，您可以编写一个比较函数，该函数将为您提供自定义运算符名称和操作数