notes

pointers

<code>
, #include <stdio.h>
, 
, 
, int main() {
,   int x = 10;
,   int *px = &x;
,   
,   printf(DQthe value of x: %d\nDQ, x);
,   printf(DQthe address of x: %p\nDQ,&x);
,   printf(DQthe value of *px: %d\nDQ, *px);
,   printf(DQthe address of *px: %p\nDQ,&px);
, 
,   return 0;
, }
, </code>
, 
, <code>
, #include <stdio.h>
, int main()
, {
,    /* Pointer of integer type, this can hold the
,     * address of a integer type variable.
,     */
,    int *p;
, 
,    int var = 10;
, 
,    /* Assigning the address of variable var to the pointer
,     * p. The p can hold the address of var because var is
,     * an integer type variable.
,     */
,    p= &var;
,    *p = 11;
,    printf(DQValue of variable var is: %dDQ, var);
,    printf(DQ\nValue of what *p is pointing to (var): %dDQ, *p);
,    printf(DQ\nAddress of variable var (&var) is: %pDQ, &var);
,    printf(DQ\nAddress of variable var (p) is: %pDQ, p);
,    printf(DQ\nAddress of pointer p is: %pDQ, &p);
,    return 0;
, }
, 
, output:
, Value of variable var is: 11
, Value of what *p is pointing to (var): 11
, Address of variable var (&var) is: 0x7ffc2d7d33ac
, Address of variable var (p) is: 0x7ffc2d7d33ac
, Address of pointer p is: 0x7ffc2d7d33b0
, 
, 
, </code>
, 
, Dereferencing is used to access or manipulate data contained in \\
, memory location pointed to by a pointer. \\
, *(asterisk) is used with pointer variable when dereferencing the pointer variable,\\ 
, it refers to variable being pointed, so this is called dereferencing of pointers.\\
, 
, <code>
, #include <stdio.h>
, 
, int main()
, {
,   
,    int a = 7, b ;
,    int *ptr; // Un-initialized Pointer
,    ptr = &a; // Stores address of a in ptr
,    b = *ptr; // Put Value at ptr in b  
,    
,    printf(DQThe contents of b: %d\nDQ, b);
,   
,   return 0;
, }
,    
, </code>