How To Access Memory Address In C

In C, there are several ways to access memory addresses or work with them. Here are the main methods:

1. Using the Address of Operator (&)

The & operator is the primary way to get the address of a variable in C. You can use it on variables to retrieve their memory addresses.

int x = 10;
int *ptr = &x; // ptr now holds the address of x
printf("Address of x: %p\n", &x);

Output

Address of x: 000000000061FE14

2. Using Pointers

Pointers are variables that store memory addresses. They allow indirect access to other variables’ values using their addresses.

int x = 10;
int *ptr = &x; // Pointer to x
printf("Address of x: %p\n", ptr); // Casting ptr to (void*) for portability
return 0;

Output

Address of x: 000000000061FE14

3. Using Arrays

In C, array names act as pointers to their first elements. Accessing an array element’s address can be done using indexing or the & operator.

int arr[3] = {1, 2, 3};
printf("Address of first element: %p\n", (void*)&arr[0]);

Output

Address of first element: 000000000061FE14

4. Using malloc(), calloc(), or realloc()

These functions allocate memory dynamically and return a pointer to the allocated memory block.

int *ptr = malloc(5 * sizeof(int)); // Allocates memory for 5 integers

if (ptr != NULL) {
printf("Address of allocated memory: %p\n", (void*)ptr); // Corrected cast to (void*)
} else {
printf("Memory allocation failed.\n");
return 1; // Return an error code if memory allocation fails
}

free(ptr); // Free the memory when done

Output

Address of allocated memory: 0000000000761480

5. Using &(*pointer) Notation

Although redundant, you can use &(*pointer) to access the address of the variable that the pointer points to. It is equivalent to using just the pointer itself.

int x = 10;
int *ptr = &x;
printf("Address of x using &(*ptr): %p\n", &(*ptr));

Output

Address of x using &(*ptr): 000000000061FE14