D语言嵌套循环

发布于 2015-08-16 14:56:09 | 91 次阅读 | 评论: 0 | 来源: 网络整理

D编程语言允许使用一个循环里嵌套另一个循环。以下部分显示几个例子来说明这一概念。

语法

语法嵌套在D环语句如下：

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

在D编程语言while循环语句语法嵌套如下：

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

嵌套do...while的语法在D编程语言循环语句如下：

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

}while( condition );

在循环嵌套最后需要说明的是，可以把任何类型的循环的任何其他类型的循环里面。例如，一个for循环可以放在一个while循环中，反之亦然。

例子：

下面的程序使用一个嵌套的for循环来找出2-100的素数：

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;
}

当上面的代码被编译并执行，它会产生以下结果：

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