Question about pointers

[guitarstar26]

What follows is a very simple test to improve my understanding of C pointers. I have two pointers. The first pointer is assigned the value "Hello". Then the second pointer is set to the first pointer. Correct me if I am wrong, but now both pointers should point to the same string? Anyways, I change the contents of firstString to be "Goodbye". When I print out what both pointers are pointing to, I get "Hello" and "Goodbye". I don't understand how this is possible.

int main(int argc, char **argv)
{
	char* firstString;
	char* newString;

	firstString = "Hello";

	newString = firstString;

	firstString = "Goodbye";

	printf("The memory location pointed to by firstString is: %d\n", firstString);
	printf("The memory location pointed to by newString is: %d\n", newString);
	
	printf("\n%s",newString);
	printf("\n%s",firstString);

	getchar();

	return 0;
}

[quzah]

You are assigning the address of a string literal to the first pointer. Then you assign that value (that address) to the second pointer. Then you make the first pointer point to a different string literal. The second pointers till holds a different value. It's the same as doing this:

int x = 5, y = x;
x = 3;

x is five, and y is five, then set x to three.

Quzah.

[anduril462]

newString is not pointing to firstString (you would need a char ** for that, since you would be pointing to a char *). It's pointing to what firstString was pointing to. If it helps, think of newString = firstString as copying the address stored in firstString into newString. Then you copy a new address (of "Goodbye") into firstString. newString doesn't automatically update.

[guitarstar26]

Thank you, now I understand.

When I change firstString to "Goodbye". I'm actually pointing to a new place, not changing the data that is in the current place.