C#嵌套循環
C#允許使用一個循環內嵌套另一個循環。下麵的內容展示幾個例子來說明這個概念。
語法
嵌套 for 循環語句在C#的語法如下:
for ( init; condition; increment ) { for ( init; condition; increment ) { statement(s); } statement(s); }
嵌套 while循環語句在C#的語法如下:
while(condition) { while(condition) { statement(s); } statement(s); }
嵌套do...while在C#循環語句的語法如下:
do { statement(s); do { statement(s); }while( condition ); }while( condition );
在循環嵌套最後需要說明的是,可以把任何類型的循環的任何其他類型的循環內。例如,一個for循環可以是一個while循環裡麵,反之亦然。
例子:
下麵的程序使用嵌套for循環查找從2至100的素數:
using System; namespace Loops { class Program { static void Main(string[] args) { /* local variable definition */ int i, j; for (i = 2; i < 100; i++) { for (j = 2; j <= (i / j); j++) if ((i % j) == 0) break; // if factor found, not prime if (j > (i / j)) Console.WriteLine("{0} is prime", i); } Console.ReadLine(); } } }
當上述代碼被編譯和執行時,它產生了以下結果:
2 is prime 3 is prime 5 is prime 7 is prime 11 is prime 13 is prime 17 is prime 19 is prime 23 is prime 29 is prime 31 is prime 37 is prime 41 is prime 43 is prime 47 is prime 53 is prime 59 is prime 61 is prime 67 is prime 71 is prime 73 is prime 79 is prime 83 is prime 89 is prime 97 is prime