D編程語(yǔ)言允許在一個(gè)循環(huán)中嵌套另一個(gè)循環(huán)。

nested loops - 語(yǔ)法

嵌套FOR LOOP語(yǔ)句的語(yǔ)法如下所示:-

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

嵌套WHILE LOOP語(yǔ)句的語(yǔ)法如下所示:-

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

嵌套DO.WHILE LOOP語(yǔ)句的語(yǔ)法如下所示:-

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

}while( condition );

關(guān)于循環(huán)嵌套的最后一個(gè)注意事項(xiàng)是，您可以將任何類(lèi)型的循環(huán)放在任何其他類(lèi)型的循環(huán)中，例如，for循環(huán)可以在while循環(huán)中，反之亦然。

nested loops - 示例

下面的程序使用嵌套的FOR循環(huán)來(lái)查找從2到100-的素?cái)?shù)

import std.stdio;
 
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)) writefln("%d is prime", i);
   }
 
   return 0;
}

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