C编程语言允许使用一个循环内嵌套的另一个循环。下面的内容展示几个例子来说明这个概念。
语法
在C语言中嵌套for语句循环的语法如下：
for ( init; condition; increment ) { for ( init; condition; increment ) { statement(s); } statement(s); }
在C编程语言中嵌套while循环声明的语法如下：
while(condition) { while(condition) { statement(s); } statement(s); }
在C编程语言嵌套do...while循环语句的语法如下：
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内。例如，对于环可以是一个while循环，或反之亦然内部。
例子：
下面的程序使用嵌套for循环从2至100找出素数：
#include <stdio.h> 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)) printf("%d is prime ", i); } return 0; }
当上述代码被编译和执行时，它产生了以下结果：
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
