Benefits of pointers?

Question

I recently developed an interest in C programming so I got myself a book (K&R) and started studying.

Coming from a University course in Java (basics), pointers a

Answer 1

Considering that you're coming from a Java background, here's the simplest way to get your head around what use pointers have.

Let's say you have a class like this in Java:

public class MyClass {
    private int myValue;

    public int getMyValue() { return myValue; }
    public void setMyValue(int value) { myValue = value; }
}

Here's your main function, that creates one of your objects and calls a function on it.

public static void Main(String[] args) {
    MyClass myInstance = new MyClass();

    myInstance.setMyValue(1);
    System.out.printLn(myInstance.getMyValue()); // prints 1

    DoSomething(myInstance);
    System.out.printLn(myInstance.getMyValue()); // prints 2
}

public static void DoSomething(MyClass instance) {
    instance.setMyValue(2);
}

The myInstance variable you declared in Main is a reference. It's basically a handle that the JVM uses to keep tabs on your object instance. Now, let's do the same thing in C.

typedef struct _MyClass
{
    int myValue;
} MyClass;

void DoSomething(MyClass *);

int main()
{
    MyClass myInstance;

    myInstance.myValue = 1;
    printf("i", myInstance.myValue); // prints 1

    MyClass *myPointer = &myInstance; // creates a pointer to the address of myInstance

    DoSomething(myPointer);
    printf("i", myInstance.myValue); // prints 2

    return 0;
}

void DoSomething(MyClass *instance)
{
    instance->myValue = 2;
}

Of course, pointers are much more flexible in C, but this is the gist of how they work in a Java sort of way.