D 语言 - 嵌套循环
D 编程语言允许在一个循环内使用另一个循环。 以下部分显示了一些示例来说明该概念。
语法
嵌套 for 循环语句的语法如下 −
for ( init; condition; increment ) {
for ( init; condition; increment ) {
statement(s);
}
statement(s);
}
嵌套 while 循环语句的语法如下 −
while(condition) {
while(condition) {
statement(s);
}
statement(s);
}
嵌套 do...while 循环语句的语法如下 −
do {
statement(s);
do {
statement(s);
}while( condition );
}while( condition );
关于循环嵌套的最后一点是，您可以将任何类型的循环放在任何其他类型的循环内。 例如，for 循环可以位于 while 循环内，反之亦然。
示例
下面的程序使用嵌套的 for 循环来查找 2 到 100 之间的素数 −
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; // 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时，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
