D語言嵌套循環

D編程語言允許使用一個循環裏嵌套另一個循環。以下部分顯示幾個例子來說明這一概念。

語法

語法嵌套在D環語句如下：

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

在D編程語言while循環語句語法嵌套如下：

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

嵌套do...while的語法在D編程語言循環語句如下：

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

在循環嵌套最後需要說明的是，可以把任何類型的循環的任何其他類型的循環裏面。例如，一個for循環可以放在一個while循環中，反之亦然。

例子：

下面的程序使用一個嵌套的for循環來找出2-100的素數：

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; }

當上面的代碼被編譯並執行，它會產生以下結果：

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