C#運算子

運算子只是一個用於執行操作的符號。可以有許多型別的操作，如算術，邏輯，按位元等運算操作。
有以下型別的運算子可以在 C# 語言中執行不同型別的操作運算。

• 算術運算子
• 關係運營商
• 邏輯運算子
• 按位元運算子
• 賦值運算子
• 其它運算子

1. 算術運算子

下面範例程式碼演示 C# 如何使用算術運算子。假設變數A的值為：10，變數B的值為：20，參考以下範例程式碼：

using System;
namespace OperatorsAppl 
{
   class Program 
   { 
      static void Main(string[] args) 
      { 
         int a = 21;
         int b = 10;
         int c;

         c = a + b;
         Console.WriteLine("Line 1 - Value of c is {0}", c);
         c = a - b;
         Console.WriteLine("Line 2 - Value of c is {0}", c);
         c = a * b;
         Console.WriteLine("Line 3 - Value of c is {0}", c);
         c = a / b;
         Console.WriteLine("Line 4 - Value of c is {0}", c);
         c = a % b;
         Console.WriteLine("Line 5 - Value of c is {0}", c);
         c = a++;
         Console.WriteLine("Line 6 - Value of c is {0}", c);
         c = a--;
         Console.WriteLine("Line 7 - Value of c is {0}", c);
         Console.ReadLine();
      }
   }
}

當編譯和執行上述程式碼時，會產生以下結果：

Line 1 - Value of c is 31
Line 2 - Value of c is 11
Line 3 - Value of c is 210
Line 4 - Value of c is 2
Line 5 - Value of c is 1
Line 6 - Value of c is 22
Line 7 - Value of c is 20

2. 關係運算子

下面範例程式碼演示 C# 如何使用關係運算子。 假設變數A的值為：10，變數B的值為：20，參考以下範例程式碼：

using System;
class Program
{
   static void Main(string[] args)
   {
      int a = 21;
      int b = 10;

      if (a == b)
      {
         Console.WriteLine("Line 1 - a is equal to b");
      }
      else 
      {
         Console.WriteLine("Line 1 - a is not equal to b");
      }

      if (a < b)
      {
         Console.WriteLine("Line 2 - a is less than b");
      }
      else
      {
         Console.WriteLine("Line 2 - a is not less than b");
      }

      if (a > b)
      {
         Console.WriteLine("Line 3 - a is greater than b");
      }
      else
      {
         Console.WriteLine("Line 3 - a is not greater than b");
      }
      /* Lets change value of a and b */
      a = 5;
      b = 20;

      if (a <= b) 
      { 
         Console.WriteLine("Line 4 - a is either less than or equal to  b");
      }

      if (b >= a)
      {
         Console.WriteLine("Line 5-b is either greater than or equal to b");
      }
   }
}

當編譯和執行上述程式碼時，會產生以下結果：

Line 1 - a is not equal to b
Line 2 - a is not less than b
Line 3 - a is greater than b
Line 4 - a is either less than or equal to b
Line 5 - b is either greater than or equal to b

3. 邏輯運算子

下面範例程式碼演示 C# 如何使用邏輯運算子。 假設變數A是一個布林值：true，變數B是一個布林值：false，參考以下範例程式碼：

using System;
namespace OperatorsAppl 
{
   class Program 
   {
      static void Main(string[] args) 
      {
         bool a = true; 
         bool b = true;

         if (a && b)
         {
            Console.WriteLine("Line 1 - Condition is true");
         }

         if (a || b)
         {
            Console.WriteLine("Line 2 - Condition is true");
         }
         /* lets change the value of  a and b */
         a = false;
         b = true;

         if (a && b)
         {
            Console.WriteLine("Line 3 - Condition is true");
         }
         else
         {
            Console.WriteLine("Line 3 - Condition is not true");
         }

         if (!(a && b))
         {
            Console.WriteLine("Line 4 - Condition is true");
         }
         Console.ReadLine();
      }
   }
}

當編譯和執行上述程式碼時，會產生以下結果：

Line 1 - Condition is true
Line 2 - Condition is true
Line 3 - Condition is not true
Line 4 - Condition is true

4. 位運算子

下面將通過範例來演示 C# 如何使用按位元運算子。 假設變數A的值為:60，變數B的值為:13，參考以下範例程式碼：

using System;
namespace OperatorsAppl
{
   class Program
   {
      static void Main(string[] args)
      {
         int a = 60;            /* 60 = 0011 1100 */ 
         int b = 13;            /* 13 = 0000 1101 */
         int c = 0; 

         c = a & b;             /* 12 = 0000 1100 */ 
         Console.WriteLine("Line 1 - Value of c is {0}", c );

         c = a | b;             /* 61 = 0011 1101 */
         Console.WriteLine("Line 2 - Value of c is {0}", c);

         c = a ^ b;             /* 49 = 0011 0001 */
         Console.WriteLine("Line 3 - Value of c is {0}", c);

         c = ~a;                /*-61 = 1100 0011 */
         Console.WriteLine("Line 4 - Value of c is {0}", c);

         c = a << 2;      /* 240 = 1111 0000 */
         Console.WriteLine("Line 5 - Value of c is {0}", c);

         c = a >> 2;      /* 15 = 0000 1111 */
         Console.WriteLine("Line 6 - Value of c is {0}", c);
         Console.ReadLine();
      }
   }
}

當編譯和執行上述程式碼時，會產生以下結果：

Line 1 - Value of c is 12
Line 2 - Value of c is 61
Line 3 - Value of c is 49
Line 4 - Value of c is -61
Line 5 - Value of c is 240
Line 6 - Value of c is 15

5. 賦值運算子

有關 C# 如何使用賦值運算子，請參考以下範例程式碼：

using System;
namespace OperatorsAppl 
{
   class Program
   {
      static void Main(string[] args)
      {
         int a = 21;
         int c;
         c = a;
         Console.WriteLine("Line 1 - =  Value of c = {0}", c);

         c += a;
         Console.WriteLine("Line 2 - += Value of c = {0}", c);

         c -= a;
         Console.WriteLine("Line 3 - -=  Value of c = {0}", c);

         c *= a;
         Console.WriteLine("Line 4 - *=  Value of c = {0}", c);

         c /= a;
         Console.WriteLine("Line 5 - /=  Value of c = {0}", c);

         c = 200;
         c %= a;
         Console.WriteLine("Line 6 - %=  Value of c = {0}", c);

         c <<= 2;
         Console.WriteLine("Line 7 - <<=  Value of c = {0}", c);

         c >>= 2;
         Console.WriteLine("Line 8 - >>=  Value of c = {0}", c);

         c &= 2;
         Console.WriteLine("Line 9 - &=  Value of c = {0}", c);

         c ^= 2;
         Console.WriteLine("Line 10 - ^=  Value of c = {0}", c);

         c |= 2;
         Console.WriteLine("Line 11 - |=  Value of c = {0}", c);
         Console.ReadLine();
      }
   }
}

當編譯和執行上述程式碼時，會產生以下結果：

Line 1 - = Value of c = 21
Line 2 - += Value of c = 42
Line 3 - -= Value of c = 21
Line 4 - *= Value of c = 441
Line 5 - /= Value of c = 21
Line 6 - %= Value of c = 11
Line 7 - <<= Value of c = 44
Line 8 - >>= Value of c = 11
Line 9 - &= Value of c = 2
Line 10 - ^= Value of c = 0
Line 11 - |= Value of c = 2

6. 其他運算子

還有其他幾個重要的操作符，包括sizeof，typeof和?:等也被 C# 支援。請參考以下範例程式碼：

using System;
namespace OperatorsAppl 
{
   class Program
   {
      static void Main(string[] args)
      {
         /* example of sizeof operator */
         Console.WriteLine("The size of int is {0}", sizeof(int));
         Console.WriteLine("The size of short is {0}", sizeof(short));
         Console.WriteLine("The size of double is {0}", sizeof(double));

         /* example of ternary operator */
         int a, b;
         a = 10;
         b = (a == 1) ? 20 : 30;
         Console.WriteLine("Value of b is {0}", b);

         b = (a == 10) ? 20 : 30;
         Console.WriteLine("Value of b is {0}", b);
         Console.ReadLine();
      }
   }
}

當編譯和執行上述程式碼時，會產生以下結果：

The size of int is 4
The size of short is 2
The size of double is 8
Value of b is 30
Value of b is 20

7. C# 中的運算子優先順序

運算子的優先順序指定哪個運算子將被首先評估計算。關聯性指定要評估的操作符方向，可以是左到右，或從右到左。

下面給出一個優先順序的例子程式碼：

int data= 10+ 5*5 ;

data變數最後的計算值為：35，因為*(乘法運算子)在+(加法運算子)之前求值。

C語言運算子的優先順序和關聯性如下：

範例

using System;
namespace OperatorsAppl
{
   class Program
   {
      static void Main(string[] args)
      {
         int a = 20;
         int b = 10;
         int c = 15;
         int d = 5;
         int e;
         e = (a + b) * c / d;     // ( 30 * 15 ) / 5
         Console.WriteLine("Value of (a + b) * c / d is : {0}", e);

         e = ((a + b) * c) / d;   // (30 * 15 ) / 5
         Console.WriteLine("Value of ((a + b) * c) / d is  : {0}", e);

         e = (a + b) * (c / d);   // (30) * (15/5)
         Console.WriteLine("Value of (a + b) * (c / d) is  : {0}", e);

         e = a + (b * c) / d;    //  20 + (150/5)
         Console.WriteLine("Value of a + (b * c) / d is  : {0}", e);
         Console.ReadLine();
      }
   }
}

當編譯和執行上述程式碼時，會產生以下結果：

Value of (a + b) * c / d is : 90
Value of ((a + b) * c) / d is  : 90
Value of (a + b) * (c / d) is  : 90
Value of a + (b * c) / d is  : 50