Skip to main content

Learn to use Pointers in C++

For those of you who do not know what pointers are, I give you a short definition. Pointer is a type of variable that stores memory addresses rather than simple data. Pointers also have Data Types associated with it, Ex. int pointers can only store memory address of int variables and similarly float pointers can only store memory address of float variables.

Pointers are one of the most important distinct features of C++. It gives the programmers power and control over several things.

Pointers have many uses; sometimes it is used as the faster means of accessing arrays while sometimes it is implemented so that the function in C++ can modify the parameters passed to it.

Pointers are extensively used in C++, this might not be obvious to you right now but as you start programming some complex program, you will notice how important pointers are.

This article would serve as a little introduction to pointers in C++, it would help you understand what pointers are and how it is used in C++.

Declaration of Pointer: Syntax: data_type *pointer_name; Please note that the * here is NOT the same as the 'value at' operator discussed below. Example: int *p;

The & Operator: As we know that every variable has two things associated with it 1)value 2) memory address of the variable. The & operator returns the memory address of a variable.It is known as the ‘address of’ operator. Example: int a; int *p; p=&a;//stores the memory address of variable 'a'

Increment/Decrement Operation on pointers: Like regular variables pointers can also be incremented/decremented If we increment a variable having value 10 then its new value will be 11, but if we increment a pointer it will point to the next memory location of its type. It is illustrated in the second program. The * Operator: It is known as the ‘value at’ operator. It returns the value at the memory address pointed by a pointer. The uses of these two operators are illustrated below:

   //C++ program to illustrate the use of * and & operators
   #include<iostream.h>
   void main(void)
   {
   int a;
   int *p;
   p=&a;//'&' is known as the 'address of'
   //operator it returns the memory address of
   //the variablein this case it is returning
   //the memory address of integer variable a
   cout<<"enter any number: ";
   cin>>a;
   cout<<endl<<"address of variable a: "<<p;
   cout<<endl<<"value at "<<p<<" "<<*p;
   cout<<endl<<"enter another number: ";
   cin>>*p;
   cout<<endl<<"value of *p: "<<*p;
   cout<<endl
   }

Have a look at the program below. In this program you’ll see how arrays are accessed using pointers.

    //C++ program to show how array elements
   //are accessed with the help of pointers
   #include<iostream.h>
   void main(void)
   {
   int arr[5]={4,8,9,2,0};
   int *p;
   p=&arr[0];//'&' is known as the 'address of'
   //operator it returns the memory address
   //of the variable in this case it is returning
   //the memory address of array arr[0]
   cout<<"address of arr[0]: "<<p;
   cout<<" value at address"<<p<<" "<<*p;
   cout<<endl;
   p++;//now 'p' is pointing to the next element
       //of the array i.e. 8
   cout<<"address of arr[1]: "<<p;
   cout<<" value at address"<<p<<" "<<*p;
   cout<<endl;
   p++;
   cout<<"address of arr[2]: "<<p;
   cout<<" value at address"<<p<<" "<<*p;
   cout<<endl;
   p++;
   cout<<"address of arr[3]: "<<p;
   cout<<" value at address"<<p<<" "<<*p;
   cout<<endl;
   p++;
   cout<<"address of arr[4]: "<<p;
   cout<<" value at address"<<p<<" "<<*p;
   cout<<endl;
   }

Pointer in C++ is a very vast topic (it has separate books written on it) so we will be discussing it in detail in the coming articles (knowing that the discussion on pointer once started, never gets end!)

Popular posts from this blog

Fix For Toshiba Satellite "RTC Battery is Low" Error (with Pictures)

RTC Battery is Low Error on a Toshiba Satellite laptop "RTC Battery is Low..." An error message flashing while you try to boot your laptop is enough to panic many people. But worry not! "RTC Battery" stands for Real-Time Clock battery which almost all laptops and PCs have on their motherboard to power the clock and sometimes to also keep the CMOS settings from getting erased while the system is switched off.  It is not uncommon for these batteries to last for years before requiring a replacement as the clock consumes very less power. And contrary to what some people tell you - they are not rechargeable or getting charged while your computer or laptop is running. In this article, we'll learn everything about RTC batteries and how to fix the error on your Toshiba Satellite laptop. What is an RTC Battery? RTC or CMOS batteries are small coin-shaped lithium batteries with a 3-volts output. Most laptops use

The Best Way(s) to Comment out PHP/HTML Code

PHP supports various styles of comments. Please check the following example: <?php // Single line comment code (); # Single line Comment code2 (); /* Multi Line comment code(); The code inside doesn't run */ // /* This doesn NOT start a multi-line comment block /* Multi line comment block The following line still ends the multi-line comment block //*/ The " # " comment style, though, is rarely used. Do note, in the example, that anything (even a multi-block comment /* ) after a " // " or " # " is a comment, and /* */ around any single-line comment overrides it. This information will come in handy when we learn about some neat tricks next. Comment out PHP Code Blocks Check the following code <?php //* Toggle line if ( 1 ) {      // } else {      // } //*/ //* Toggle line if ( 2 ) {      // } else {      // } //*/ Now see how easy it is to toggle a part of PHP code by just removing or adding a single " / " from th

Designing a Simple Order Form Application in PHP

Ok guys, for this post we’re going to create a simple yet complete order form page. Order forms are used on many sites to take customers order online. Order forms should have the capability to take orders from visitors regarding what items they want to purchase and store the information for further processing. For this post’s example, we are going to create an order form for a Book Seller. The form will be designed to take order of five different items (books). Our order form application should be able to take order of five different items in any separate quantities tht user wants, it should also ask for shipping address and name of the customer. It should then store the information provided in a file along with the date and time order was placed. The application should also be able to take any number of orders and store them all linearly for further human processing. For this, we need a front end of a HTML form to which the user would interact a