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。
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
