Objective-C 嵌套循環(huán)

Objective-C語言的編程語言允許使用一個循環(huán)的另一循環(huán)內(nèi)。下面的部分顯示了幾個例子來說明這個概念。

語法:

嵌套的for循環(huán)語句在C的語法如下：

for ( init; condition; increment )
{
   for ( init; condition; increment )
   {
      statement(s);
   }
   statement(s);
}

 nested while loop 語句的語法在Objective-C編程語言的語句如下：

while(condition)
{
   while(condition)
   {
      statement(s);
   }
   statement(s);
}

嵌套 nested do...while loop 語句語法在Objective-C編程語言的語句如下：

do
{
   statement(s);
   do
   {
      statement(s);
   }while( condition );

}while( condition );

循環(huán)嵌套最后需要說明的是，你可以把任何類型的循環(huán)內(nèi)的任何其他類型的循環(huán)。例如，一個for循環(huán)，可以在while循環(huán)或反之亦然。

例如：

下面的程序使用嵌套的for循環(huán)找出2?100中的素數(shù)

#import <Foundation/Foundation.h>
 
int main ()
{
   /* local variable definition */
   int i, j;
   
   for(i=2; i<100; i++) {
      for(j=2; j <= (i/j); j++)
        if(!(i%j)) break; // if factor found, not prime
      if(j > (i/j)) NSLog(@"%d is prime
", i);
   }
 
   return 0;
}

上面的代碼編譯和執(zhí)行時，它會產(chǎn)生以下結(jié)果：

2013-09-07 22:40:01.004 demo[1027] 2 is prime
2013-09-07 22:40:01.005 demo[1027] 3 is prime
2013-09-07 22:40:01.005 demo[1027] 5 is prime
2013-09-07 22:40:01.005 demo[1027] 7 is prime
2013-09-07 22:40:01.005 demo[1027] 11 is prime
2013-09-07 22:40:01.005 demo[1027] 13 is prime
2013-09-07 22:40:01.005 demo[1027] 17 is prime
2013-09-07 22:40:01.005 demo[1027] 19 is prime
2013-09-07 22:40:01.005 demo[1027] 23 is prime
2013-09-07 22:40:01.005 demo[1027] 29 is prime
2013-09-07 22:40:01.005 demo[1027] 31 is prime
2013-09-07 22:40:01.005 demo[1027] 37 is prime
2013-09-07 22:40:01.005 demo[1027] 41 is prime
2013-09-07 22:40:01.005 demo[1027] 43 is prime
2013-09-07 22:40:01.005 demo[1027] 47 is prime
2013-09-07 22:40:01.005 demo[1027] 53 is prime
2013-09-07 22:40:01.005 demo[1027] 59 is prime
2013-09-07 22:40:01.005 demo[1027] 61 is prime
2013-09-07 22:40:01.005 demo[1027] 67 is prime
2013-09-07 22:40:01.005 demo[1027] 71 is prime
2013-09-07 22:40:01.005 demo[1027] 73 is prime
2013-09-07 22:40:01.005 demo[1027] 79 is prime
2013-09-07 22:40:01.005 demo[1027] 83 is prime
2013-09-07 22:40:01.005 demo[1027] 89 is prime
2013-09-07 22:40:01.005 demo[1027] 97 is prime