CODEWITHSUNDEEP
cpointers
net_man
net_man

Reputation: 49

difference between address of pointer to char and pointer to pointer to char

I have following sample of code:

#include <stdio.h>

int main(void)
{
   char *text[2];
   text[0] = "Hello";
   text[1] = "World";

   printf("Address of text[0]: %p\n", text[0]);
   printf("Address of text   : %p\n", text);

   return 0;
}

The output of this program is:

Address of text[0]: 0x400694
Address of text   : 0x7ffcac41b000

I am wondering why these addresses differ in length. Why is address of first pointer to char only 6 digits length?

Upvotes: 3

Views: 95

Answers (4)

4pie0
4pie0

Reputation: 29724

printf("Address of text[0]: %p\n", text[0]);

prints the address of C string (the address first element of array points to), while:

printf("Address of text   : %p\n", text);

prints the address of array's first element.

Upvotes: 0

Rudy Velthuis
Rudy Velthuis

Reputation: 28806

To get the address of the first item of the array text, you'll have to use:

printf("Address of text[0]: %p\n", (void *)&text[0]);

In your question, you are printing the address of the first character of the string "Hello" (in other words, of the content of text[0]), not the address of the first element of the array text, i.e. not the address of text[0], just the address stored in text[0].

Upvotes: 0

Amit
Amit

Reputation: 46323

There is no difference in "address length", the difference is in the value.

In this particular case, I assume the text[0] pointer points to a data segment that holds the compile time value "Hello", and the text pointer points to a runtime address.

Since these are at different memory segments, they can be "very far" and so you get the output you see.

Upvotes: 3

Mike Nakis
Mike Nakis

Reputation: 61969

The first address is the address of "Hello", which is stored in your data segment.

The second address is the address of text[], which is stored in your stack.

These two areas of memory are far from each other, so one has many digits, the other has few digits.

Apparently, %p renders only as many digits as necessary to represent the address.

Upvotes: 2

Related Questions