D语言 中的 nested 循环函数

D编程语言允许在一个循环中嵌套另一个循环。

nested loops - 语法

嵌套FOR LOOP语句的语法如下所示:-

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

嵌套WHILE LOOP语句的语法如下所示:-

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

嵌套DO.WHILE LOOP语句的语法如下所示:-

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

}while( condition );

关于循环嵌套的最后一个注意事项是，您可以将任何类型的循环放在任何其他类型的循环中，例如，for循环可以在while循环中，反之亦然。

nested loops - 示例

下面的程序使用嵌套的FOR循环来查找从2到100-的素数

import std.stdio;
 
int main () {
   /* 局部变量定义 */
   int i, j;
   
   for(i=2; i<100; i++) {
      for(j=2; j <= (i/j); j++)
        if(!(i%j)) break; //如果找到因子，则不是素数
      if(j > (i/j)) writefln("%d is prime", i);
   }
 
   return 0;
}

编译并执行上述代码时，将生成以下结果-

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