|| 运算符（C# 参考）
条件或运算符 (||) 执行的逻辑或其 bool 操作数。如果第一个操作数计算结果为 true，第二个操作数对象不会计算。如果第一个操作数计算结果为 false，第二个运算符确定或表达式整体是否计算结果为 true 或 false。
备注
操作
x || y
对应于操作
x | y
但，如果 x 是 true，y 不会计算无论 y，的值，因为或操作是 true。此概念称为“短路计算”。
条件或运算符无法重载，但是，公共逻辑运算符和 真 和 假 运算符的重载，有一些限制的，也将条件逻辑运算符的重载。
示例
在下面的示例中，表达式中使用的 || 计算只有第一个操作数。使用的表达式|计算两个操作数。在第二个示例中，因此，如果两个操作数计算，则运行时会发生异常。
class ConditionalOr
{
// Method1 returns true.
static bool Method1()
{
Console.WriteLine("Method1 called.");
return true;
}
// Method2 returns false.
static bool Method2()
{
Console.WriteLine("Method2 called.");
return false;
}
static bool Divisible(int number, int divisor)
{
// If the OR expression uses ||, the division is not attempted
// when the divisor equals 0.
return !(divisor == 0 || number % divisor != 0);
// If the OR expression uses |, the division is attempted when
// the divisor equals 0, and causes a divide-by-zero exception.
// Replace the return statement with the following line to
// see the exception.
//return !(divisor == 0 | number % divisor != 0);
}
static void Main()
{
// Example #1 uses Method1 and Method2 to demonstrate
// short-circuit evaluation.
Console.WriteLine("Regular OR:");
// The | operator evaluates both operands, even though after
// Method1 returns true, you know that the OR expression is
// true.
Console.WriteLine("Result is {0}.\n", Method1() | Method2());
Console.WriteLine("Short-circuit OR:");
// Method2 is not called, because Method1 returns true.
Console.WriteLine("Result is {0}.\n", Method1() || Method2());
// In Example #2, method Divisible returns True if the
// first argument is evenly divisible by the second, and False
// otherwise. Using the | operator instead of the || operator
// causes a divide-by-zero exception.
// The following line displays True, because 42 is evenly
// divisible by 7.
Console.WriteLine("Divisible returns {0}.", Divisible(42, 7));
// The following line displays False, because 42 is not evenly
// divisible by 5.
Console.WriteLine("Divisible returns {0}.", Divisible(42, 5));
// The following line displays False when method Divisible
// uses ||, because you cannot divide by 0.
// If method Divisible uses | instead of ||, this line
// causes an exception.
Console.WriteLine("Divisible returns {0}.", Divisible(42, 0));
}
}
/*
Output:
Regular OR:
Method1 called.
Method2 called.
Result is True.
Short-circuit OR:
Method1 called.
Result is True.
Divisible returns True.
Divisible returns False.
Divisible returns False.
*/