#include<stdio.h>

main()
{
    int a, b, c, d;
   
    for(a=1; a<=5; a++)                           
    {           
        for(d=8; d>=2*a-1; d--)
        {
            printf(" ");
        }
        for(b=1; b<=2*a-1; b++)
        {
            for(c=2; c<=b; c++)                                        *
            {                                                        * * *
                if(c%2==0)                                         * * * * *
                    printf(" ");                                 * * * * * * *
                else                                           * * * * * * * * *
                    break;
            }
            printf("*");
        }
        printf("\n\n");
    }
------------------------------
------------------------------
    for(a=4; a>=1; a--)
    {
        for(d=8; d>=2*a-1; d--)                                  * * * * * * *
            printf(" ");                                           * * * * *
        for(b=1; b<=2*a-1; b++)                                      * * *
        {                                                              *
            for(c=2; c<=b; c++)
            {
                if(c%2==0)
                    printf(" ");
                else
                    break;
            }
            printf("*");
        }
        printf("\n\n");
    }
    getch();
}

程序最后输出的是一个由 * 号组成的完整的棱形，  在上面分开输出来只是说明两个 for 循环的不同输出。 请高手帮忙简化下程序， 只用for或while或if等结构。。  谢谢！

因为是初学C语言， 所以5楼的程序还看不太明白。
很感谢大家给的各种不同的方法。

感谢给我解题的另一种思路