break（C# 参考）

break 语句用于终止最近的封闭循环或它所在的 switch 语句。控制传递给终止语句后面的语句（如果有的话）。

在此示例中，条件语句包含一个应从 1 计数到 100 的计数器；但 break 语句在计数器计数到 4 后终止了循环。

class BreakTest
{
    static void Main()
    {
        for (int i = 1; i <= 100; i++)
        {
            if (i == 5)
            {
                break;
            }
            Console.WriteLine(i);
        }

        // Keep the console open in debug mode.
        Console.WriteLine("Press any key to exit.");
        Console.ReadKey();
    }
}
/* 
 Output:
    1
    2
    3
    4  
*/

在此示例中，break 语句用于中断内层嵌套循环，并将控制权返回给外层循环。

class BreakInNestedLoops
{
    static void Main(string[] args)
    {

        int[] numbers = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
        char[] letters = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j' };

        // Outer loop
        for (int x = 0; x < numbers.Length; x++)
        {
            Console.WriteLine("num = {0}", numbers[x]);

            // Inner loop
            for (int y = 0; y < letters.Length; y++)
            {
                if (y == x)
                {
                    // Return control to outer loop
                    break;
                }
                Console.Write(" {0} ", letters[y]);
            }
            Console.WriteLine();
        }

        // Keep the console open in debug mode.
        Console.WriteLine("Press any key to exit.");
        Console.ReadKey();
    }
}

/*
 * Output:
    num = 0

    num = 1
     a
    num = 2
     a  b
    num = 3
     a  b  c
    num = 4
     a  b  c  d
    num = 5
     a  b  c  d  e
    num = 6
     a  b  c  d  e  f
    num = 7
     a  b  c  d  e  f  g
    num = 8
     a  b  c  d  e  f  g  h
    num = 9
     a  b  c  d  e  f  g  h  i
 */

下面的示例演示 break 在 switch 语句中的用法。

class Switch
{
    static void Main()
    {
        Console.Write("Enter your selection (1, 2, or 3): ");
        string s = Console.ReadLine();
        int n = Int32.Parse(s);

        switch (n)
        {
            case 1:
                Console.WriteLine("Current value is {0}", 1);
                break;
            case 2:
                Console.WriteLine("Current value is {0}", 2);
                break;
            case 3:
                Console.WriteLine("Current value is {0}", 3);
                break;
            default:
                Console.WriteLine("Sorry, invalid selection.");
                break;
        }

        // Keep the console open in debug mode.
        Console.WriteLine("Press any key to exit.");
        Console.ReadKey();
    }
}
/*
Sample Input: 1

Sample Output:
Enter your selection (1, 2, or 3): 1
Current value is 1
*/

如果输入了 4，则输出为：

Enter your selection (1, 2, or 3): 4
Sorry, invalid selection.

C# 语言规范

有关详细信息，请参阅 C# 语言规范。该语言规范是 C# 语法和用法的权威资料。

请参阅