Unlock the Power of Pointers in C Programming

Understanding Addresses in C

When you declare a variable var in your program, the compiler allocates a specific memory location to store its value. You can access this memory address using the unary operator & followed by the variable name, like &var. This address is where the value entered by the user is stored when using the scanf() function.

Let’s Get Hands-On!

Take a look at this example:

int var;
printf("%p", &var);

Run this code, and you’ll see the memory address of var printed out. Note that the address will likely be different each time you run the program.

Pointers: The Game-Changers

Pointers are special variables that store memory addresses rather than values. They’re declared using an asterisk (*) before the pointer name, like int *p. This syntax tells the compiler that p is a pointer that can hold the memory address of an int variable.

Declaring Pointers: Multiple Ways

You can declare pointers in various ways:

• int *p1, *p2; – declaring multiple pointers
• int *p; – declaring a single pointer

Assigning Addresses to Pointers

Let’s assign the address of a variable c to a pointer pc:

int c = 5;
int *pc = &c; // assigning address of c to pc

Now, pc holds the memory address of c.

Unleashing the Power of Pointers

To access the value stored at the memory address held by a pointer, use the dereference operator (*) like this:

int c = 5;
int *pc = &c;
printf("%d", *pc); // prints 5

Changing the Value Pointed by a Pointer

Let’s modify the value of c through the pointer pc:

int c = 5;
int *pc = &c;
*pc = 1; // changes the value of c to 1

Now, c is equal to 1.

Working Example: Pointers in Action

Here’s a complete program demonstrating pointer operations:

int main() {
    int c = 22;
    int *pc = &c;

    printf("Value of c: %d\n", c);
    printf("Address of c: %p\n", &c);

    *pc = 2;  // changes the value of c to 2

    printf("New value of c: %d\n", c);

    return 0;
}

Common Pitfalls to Avoid

When working with pointers, it’s essential to understand the syntax correctly. A common mistake is using int *p = &c; without realizing that p is the pointer, not *p. To avoid this confusion, use the syntax int *p; followed by p = &c;.

Now that you’ve grasped the basics of pointers, you’re ready to explore how they relate to arrays in the next tutorial.