Thread: Need Help Understand Pointers in C

Hello, New Member here !! I have just started Learning C after a long time and Started Pointers in C. I have some doubts in P+1 (Pointers arithmetic's) below i have given a example code

Code:

#include <stdio.h>

int main () 
{
    int  a = 10;   /* normal variable declaration */
    int  *p;        /* pointer variable declaration */
    p = &a;  /* store address of ‘a’ in pointer variable*/
    printf("Value of a variable: %d\n", a  );
    printf("Address of &a variable: %d\n", &a  );
    printf("\n");

    printf("Address stored in p : %d\n",p );
    printf("Value of *p: %d\n", *p );     
    printf("Address of &p variable: %d\n ", &p );
    printf("\n");

    printf("Address stored in p+1 variable: %d\n ", p+1);
    printf("Address of &p+1 variable: %d\n ", &p+1 );
    printf("value of *(p+1) variable: %d\n", *(p+1));
    printf("value of *p+1 variable: %d\n", *p+1);
    printf("\n");

    printf("Address stored in p+2 variable: %d\n ", p+2);
    printf("Address of &p+2 variable: %d\n ", &p+2);
    printf("value of *(p+2) variable: %d\n", *(p+2));
    printf("value of *p+2 variable: %d\n", *p+2);
     return 0;
}

OUTPUT :-

Code:

~/Workspace/C$ ./ pointers 
Value of a variable: 10
Address of &a variable: 1116119516

Address stored in p : 1116119516
Value of *p: 10
Address of &p : 1116119520
 
Address stored in p+1 variable: 1116119520
Address of &p+1 variable: 1116119528
value of *(p+1) variable: 1116119516
value of *p+1 variable: 11

Address stored in p+2 variable: 1116119524
Address of &p+2 variable: 1116119536
value of *(p+2) variable: 32765
value of *p+2 variable: 12

Attachment 16315

my doubt is, why Address of p (&p) and Address stored in p+1 is same. i know that by P+1 means is moving 4 bytes from the given address for integer which is p = 1116119516 + 4 --> P+1 = 1116119520, But &p is in 1116119520 before declaring P+1 which also gets 1116119520 as address. if both has same address wont there be some conflict in memory between those two if &p is called again.

doubt 2, Why is Address stored in p: 1116119516 and value of *(p+1) variable: 1116119516 is same. is't *(p+1) suppose to get some garbage value because its doesn't have a variable declared.

i don't understand this,
if made some mistake in explaining things forgive me and help clear my stupid doubt

If your still struggling to understand it try thinking of each variable (that is a and p) as a house, houses come in many sizes but always have an address and contents, the contents of house p is the address of house a, the &a/&p is saying give me the address of the house I'm pointing at, the *p is saying give follow the address contained in house p to house a and get the contents.

I don't think I missed anything there, gotta start work in a mo so I'll leave the rest to the other forum members

I would change only:

...the &a/&p is saying give me the address of the house I'm pointing at.

To

...the &a/&p is saying: give me the address of the house.

Is a is house, &a is the address of the house. Same to "house" p.

Originally Posted by flp1969

I would change only:

To

Is a is house, &a is the address of the house. Same to "house" p.

I said pointing with the image of the coder standing there literary pointing with their finger at the house, the & symbol being their finger