用C语言输出一个菱形

//输出一个菱形/*
        *
       ***
      *****
     *******
    *********
   ***********
     *********
       *******
         *****
           ***
             *
*/

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int main()
{
     int i = 0, j = 0, k = 0;
     char a[] = {"*************"};
     char b[] = {"             "};
     char c[] = {"             "};
     j = strlen(a) - 1;
     i = k = (i+j)/2;
     while (i)
     {
          b[i] = a[i];
          b[k] = a[k];
          printf ("%s\n",b);
          i --;
          k ++;
     }
     a[i]=c[i];
     a[k]= c[k];
     while (i < k)
     {
          i++;
          k--;
          a[i] = c[i];
          a[k] = c[k];
          printf ("%s\n",a);
     }
 
     system ("pause");
     return 0;
}