added uninon

C/double_pointer.c

@@ -0,0 +1,16 @@
+//double pointer example
+
+#include<stdio.h>
+
+void main()
+{
+int x, *p1, **p2;
+x = 100;
+p1 = &x; /* address of x */
+p2 = &p1; /* address of p1 */
+printf("p1 contains adress of x which is : %u\n",p1);
+printf("Address of p1 is : %u\n",&p1);
+printf("p2 contains adress of p1 which is : %u\n",p2);
+
+printf("Value of x is %d",**p2);
+}