Introduction
When you start learning C++, you come across many terms like variables, arrays, functions, and classes. One of the most powerful features provided by C++ is pointer. It gives you more control over memory, which is very important in advanced programming and system-level development.
With this article, we will take a much deeper look at pointers as to what they are, why they exist, and how to go about working with them. Therefore, read on; whether a beginner or simply looking to revise the concept, this one is for you to understand pointers very easily and clearly.
What Are Pointers in C++?
In C++, a pointer is a unique type of variable used to store the memory address of another variable. In other words, rather than holding some value, such as 5 or 10, the pointer holds where the corresponding value is stored in memory.
Example
Code:
int num = 10;
int* ptr = #
Explanation:
num is a normal integer variable.
&num gives the memory address of num.
ptr is a pointer that stores the address of num.
Therefore, the pointer doesn’t store 10; it stores where 10 is located in the computer’s memory.
Why Use Pointers in C++?
Pointers are very helpful with many tasks. Here is a small list of common reasons why pointers are important:
- Memory Efficiency
The use of pointers enables one to perform operations directly on memory. Using pointers, dynamic memory (heap memory) instead of wasting memory.
- Dynamic Memory Allocation
In C++, you can easily allocate memory with the new keyword and by using delete, you are easily deallocating memory.
- Data Structures
Using the pointers, you can easily connect data structures like linked lists, binary trees and graphs.
- Arrays and Strings
Using pointers allows you to work very efficiently with arrays and strings, especially with large data.
How to Use Pointers in C++?
Using pointers in C++ allows you to directly access and manipulate memory addresses. They are a powerful feature, especially when working with dynamic memory, arrays, functions, and data structures like linked lists.
- Declaration of Pointer
To declare a pointer in C++, we use the asterisk symbol (*) before the name of the variable.
int* ptr;
This means ptr is a pointer to an integer.
- Assigning Address to Pointer
You can assign the address of the variable using the address of the pointer (&).
int num = 20;
int* ptr = #
Now, ptr stores the address of num.
- Dereferencing a Pointer
The * operator is used to dereference a pointer; you can easily access or modify the actual value stored at the memory address.
Example:
#include
using namespace std;
int main() {
int value = 10;
int* pointer = &value;
cout << “The Original value of the variable: ” << value << endl;
cout << “Memory address of value: ” << &value << endl;
cout << “Pointer holds the address: ” << pointer << endl;
cout << “Value accessed via pointer: ” << *pointer << endl;
return 0;
}
Output:
The Original value of the variable: 10
Memory address of value: 0x7fff953e8c14
Pointer holds the address: 0x7fff953e8c14
Value accessed via pointer: 10
Pointers and Functions
Pointers allow functions to modify the actual value of arguments passed to them. It helps us avoid copying large amounts of data.
Example:
#include
using namespace std;
void changeValue(int* ptr) {
*ptr = 100;
}
int main() {
int a = 50;
changeValue(&a);
cout << a;
}
Output:
100
Dynamic Memory using Pointers
It is also known as the Run-time Memory allocation. The new and delete makes your program flexible in managing memory while the program runs. The new operator is used to allocate memory from the heap, and the delete operator is used to deallocate memory.
Example:
#include
using namespace std;
int main() {
int* ptr = new int;
*ptr = 25;
cout << *ptr;
delete ptr; // deallocates memory
return 0;
}
Output:
25
Pointers and Arrays
In C++, the name of an array is actually a pointer to its first element. It means you can use the array name to access its elements using a pointer.
Example:
#include
using namespace std;
int main() {
int arr[3] = {10, 20, 30};
int* ptr = arr;
cout << *ptr << endl;
cout << *(ptr + 1) << endl;
return 0;
}
Output:
10
20
Common Mistakes with Pointers
- Uninitialized pointers: A pointer may point to garbage memory and cause a crash due to invalid addresses.
- Memory Leak: Memory remains allocated and wasted if new is used but deleted is not.
- Dangling pointers: This happens when an object pointed to is deleted, but the pointer is still pointing to it.
Conclusion
Pointers in C++ are a very useful feature which helps you control memory and do advanced programming tasks. Now you know what pointers are, why they are used, and how to work with them in a very plain and clear way.
Pointers in C++: What, why, and how? I suggest you learn C++ Programming from the Tpoint Tech website as it provides C++ programming tutorials, interview questions, and an Online Compiler as well.
Learning pointers helps you understand how programs manage memory behind the scenes. Understanding pointers is essential if you want to build efficient and powerful C++ programs.
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