I am learning about pointers.

I was wondering how the memory address is defined in programming. I get different outputs depending on the format I choose for memory address. So I was wondering if it is correct to assume that the format of the memory address is defined by the programmer. I get different results for memory address when I use Serial.print( (long) &ptr1, DEC); and Serial.print( (long) &ptr1, HEX);

 #include <stdio.h>
 int counter = 0;
   void setup() {
    Serial.begin(9600);
   int test1 = 10; 
   float test2 = 3.14159; 
   char test3[ ] = "This is a character array";
   int *ptr1;
   float *ptr2; 
 char *ptr3; 
  ptr1 = &test1; 
Serial.print("The integer value is stored at ");
Serial.print( (long) &ptr1, DEC);


  } 
 void loop() {

    }