Diamond

/*

  *
 ***
*****
 ***
  *
  
*/

#include <stdio.h>

int main()
{

    int n, c, k, space = 1;

    printf("Enter number of rows\n");
    scanf("%d", &n);

    space = n - 1;

    for (k = 1; k <= n; k++)
    {

        for (c = 1; c <= space; c++)
            printf(" ");

        space--;

        for (c = 1; c <= 2 * k - 1; c++)
            printf("*");

        printf("\n");
    }

    space = 1;

    for (k = 1; k <= n - 1; k++)
    {

        for (c = 1; c <= space; c++)
            printf(" ");

        space++;

        for (c = 1; c <= 2 * (n - k) - 1; c++)
            printf("*");

        printf("\n");
    }

    return 0;
}

OUTPUT

Enter number of rows
4
   *
  ***
 *****
*******
 *****
  ***
   *