C# 初學者/運算子

運算子對資料執行操作。C# 中有三種類型的運算子

• 一元運算子的形式為 [運算子][物件]。例如，取反運算子：-number 會返回帶相反符號的 number（如果 number 為 12，則會返回 -12）。
• 二元運算子的形式為 [物件 1] [運算子] [物件 2]。例如，賦值運算子：number = 1234 將 number 設定為 1234。
• 三元運算子作用於三個物件。C# 只有一個三元運算子，即條件運算子：number == 1234 ? "good" : "bad" 如果 number 等於 1234，則會返回 "good"，否則返回 "bad"。

您可以幾乎以任何您喜歡的方式組合運算子。以下是一個包含許多不同運算子的示例

class OperatorsExample
{
    public static void Main()
    {
        int number = 0;
        float anotherNumber = 1.234;
        string someText = "lots of ";
        
        number = number + 4; // number is now 4
        anotherNumber += 2; // this is a shorter version of the above; it adds 2 to anotherNumber, making it 3.234
        someText += "text"; // someText now contains "lots of text"
        number = -number; // number is now -4
        anotherNumber -= number * 2; // subtracts -8 from anotherNumber, making anotherNumber 11.234.
        
        number++; // increments number, making it -3
        anotherNumber = number++; // increments number but sets anotherNumber to the original number.
        // number is now -2, and anotherNumber is -3.
        number--; // decrements number, making it -3
        anotherNumber = --number; // decrements number and sets anotherNumber to the new number.
        
        anotherNumber = number = 1; // sets both anotherNumber and number to 1.
        
        bool someBoolean;
        
        // sets someBoolean to true if anotherNumber equals number, otherwise sets it to false
        someBoolean = anotherNumber == number;
    }
}

字首和字尾

++ 和 -- 運算子可以放在變數之前（字首）或之後（字尾）。兩者之間存在細微差異；如果放在前面，則先遞增或遞減，然後返回新值；如果放在後面，則先遞增或遞減，然後返回舊值。例如

int x, y;

x = 0;
x++;
++x;

// x is now 2...
y = x++; // y is now 2, x is now 3

x = 2; // x is now 2 again...
y = ++x; // y is now 3, x is now 3