C语言 中的 嵌套函数

C 编程允许在另一个循环中使用一个循环。以下部分显示了几个示例来说明该概念。

嵌套语法

C 中嵌套 for 循环语句的语法如下 -

for ( init; condition; increment ) {

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

C 语言中嵌套 while 循环语句的语法如下：

while(condition) {

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

C 语言中嵌套 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入任何其他类型的循环中。例如，“for”循环可以在“while”循环内，反之亦然。

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嵌套循环示例

以下程序使用嵌套 for 循环来查找从 2 到 100 的素数 -

#include <stdio.h>
 
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)) printf("%d is prime\n", i);
   }
 
   return 0;
}

当上面的代码被编译和执行时，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