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Understanding Pointers in C++: Uses, Addresses, and Variables, Exercises of Computer Programming

Alagappa University Computer Programming

An introduction to pointers in c++ programming language. It explains the common uses of pointers, such as accessing array elements, passing arguments to functions, and creating data structures. The document also covers the concept of addresses and pointer variables, and demonstrates how to access the variable pointed to by a pointer. Examples and exercises are included.

Typology: Exercises

2011/2012

Uploaded on 07/31/2012

dhairya 🇮🇳

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POINTERS

What are pointers for? Here are some common

uses:

Accessing array elements

Passing arguments to a function when the function

needs to modify the original argument

Passing arrays and strings to functions

Obtaining memory from the system

Creating data structures such as linked lists

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POINTERS

 What are pointers for? Here are some common uses:  Accessing array elements  Passing arguments to a function when the function needs to modify the original argument  Passing arrays and strings to functions  Obtaining memory from the system  Creating data structures such as linked lists

POINTER

 Pointers are much more commonly used in C++ (and C) than in many other languages  In some situations pointers provide an essential tool for increasing the power of C++  Although you can do a lot of programming in C++ without using pointers, you will find them essential to obtaining the most from the language.

#include using namespace std; int main() { int var1 = 11; int var2 = 22; int var3 = 33; cout << &var1 << endl << &var2 << endl << &var3 << endl; Return 0; }

#include using namespace std; int main() { int var1 = 11; int var2 = 22; cout << &var1 << endl << &var2 << endl << endl; int* ptr; //pointer to integers ptr = &var1; //pointer points to var cout << ptr << endl; //print pointer value ptr = &var2; cout << ptr << endl; return 0; } docsity.com

POINTER VARIABLES

 What’s wrong with the idea of a general- purpose pointer type that holds pointers to any data type? If we called it type pointer we could write declarations like  pointer ptr;  The problem is that the compiler needs to know what kind of variable the pointer points to. (We’ll see why when we talk about pointers and arrays.) The syntax used in C++ allows pointers to any type to be declared.

Accessing the Variable Pointed To

 Suppose that we don’t know the name of a variable but we do know its address. Can we access the contents of the variable?  There is a special syntax to access the value of a variable using its address instead of its name. Here’s an example program

#include using namespace std; int main() { int var1, var2; int* ptr; ptr = &var1; //set pointer to address of var *ptr = 37; //same as var1= var2 = *ptr; //same as var2=var cout << var2 << endl; return 0; }

 Remember that the asterisk used as the indirection operator has a different meaning than the asterisk used to declare pointer variables. The indirection operator precedes the variable and means value of the variable pointed to by. The asterisk used in a declaration means pointer to.  int* ptr; //declaration: pointer to int  (^) *ptr = 37; //indirection: value of variable pointed to by ptr

Pointers and Arrays

#include using namespace std; int main() { int intarray[5] = { 31, 54, 77, 52, 93 }; for(int j=0; j<5; j++) cout << intarray[j] << endl; return 0; }

#include using namespace std; int main() { int intarray[5] = { 31, 54, 77, 52, 93 }; for(int j=0; j<5; j++) cout << *(intarray+j) << endl; return 0; }

#include using namespace std; int main() { int intarray[] = { 31, 54, 77, 52, 93 }; //array int* ptrint; ptrint = intarray; for(int j=0; j<5; j++) cout << *(ptrint++) << endl; return 0; }

Understanding Pointers in C++: Uses, Addresses, and Variables, Exercises of Computer Programming

Related documents

Partial preview of the text

Download Understanding Pointers in C++: Uses, Addresses, and Variables and more Exercises Computer Programming in PDF only on Docsity!

POINTERS

POINTER

POINTER VARIABLES

Accessing the Variable Pointed To

Pointers and Arrays

LAB TASK

Write a program to assign a value to a variable

using its pointer variable. Print out the value

using the variable name and also print out the

memory address of the variable using the pointer

variable?