C++ Pointer To Pointer (Double Pointer) Last Updated : 02 Aug, 2025 Comments Improve Suggest changes Like Article Like Report Now, we already know that a pointer stores the memory address of other variables. So, when we define a pointer to a pointer, the first pointer is used to store the address of the variables, and the second pointer stores the address of the first pointer. For this very reason, this is known as a Double Pointer or Pointer to Pointer.The below diagram explains the concept of Double Pointers : In a double pointer, Pointer 1 stores the address of a variable, and Pointer 2 stores the address of Pointer 1. This setup is called a pointer to pointer or double pointer.How to Declare a Pointer to a Pointer in C ++?Declaring a Pointer to Pointer is similar to declaring a pointer in C++. The difference is we have to use an additional * operator before the name of a Pointer in C++.Syntax of a Pointer to Pointer(Double Pointer) in C++:data_type_of_pointer **name_of_variable = & normal_pointer_variable;Example: C++ // C++ program to implement // pointer to pointer #include <bits/stdc++.h> using namespace std; // Driver code int main() { int variable = 169; // Pointer to store the address // of variable int* pointer1; // double pointer to store the // address of pointer1 int** pointer2; // Storing address of variable // in pointer1 pointer1 = &variable; // Storing address of pointer1 // in pointer2 pointer2 = &pointer1; // Displaying the value of variable // with using both single and double // pointers. cout << "Value of variable :- " << variable << "\n"; cout << "Value of variable using single pointer :- " << *pointer1 << "\n"; cout << "Value of variable using double pointer :- " << **pointer2 << "\n"; return 0; } OutputValue of variable :- 169 Value of variable using single pointer :- 169 Value of variable using double pointer :- 169 The below diagram explains the concept of Double Pointers: The above diagram shows the memory representation of a pointer to a pointer. The first pointer ptr1 stores the address of the variable and the second pointer ptr2 stores the address of the first pointer. What will be the size of a pointer to a pointer in C++?In the C++ programming language double pointer behave similarly to a normal pointer. So, the size of the variable of the double-pointer and the size of the normal pointer variable is always equal.Below is a C++ program to check the size of a double pointer: C++ // C++ program to check the size // of a pointer to a pointer. #include <bits/stdc++.h> using namespace std; // Driver code int main() { int val = 169; int* ptr = &val; int** double_ptr = &ptr; cout << " Size of normal Pointer: " << sizeof(ptr) << "\n"; cout << " Size of double Pointer: " << sizeof(double_ptr) << "\n"; return 0; } Output Size of normal Pointer: 8 Size of double Pointer: 8 Note: The output of the above code also depends on the type of machine which is being used. The size of a pointer is not fixed in the C++ programming language and it totally depends on other factors like CPU architecture and OS used. Usually, for a 64-bit Operating System, a size of 8 bytes memory and for a 32-bit Operating system, a size of 4 bytes memory is assigned. Comment More infoAdvertise with us S shoumikmanna Follow Improve Article Tags : Technical Scripter C++ Technical Scripter 2022 cpp-pointer Practice Tags : CPP Similar Reads C++ Programming Language C++ is a programming language known for its fast speed, low level memory management and is often taught as first programming language. Why Learn C++?C++ is often taught as a foundational language to aspiring programmers, but it is much more than that:C++ is used in making operating systems, embedded 5 min read C++ OverviewIntroduction to C++ Programming LanguageC++ is a general-purpose programming language that was developed by Bjarne Stroustrup as an enhancement of the C language to add object-oriented paradigm. It is considered as a middle-level language as it combines features of both high-level and low-level languages. It has high level language featur 3 min read Features of C++C++ is a general-purpose programming language that was developed as an enhancement of the C language to include an object-oriented paradigm. It is an imperative and compiled language. C++ has a number of features, including:Object-Oriented ProgrammingMachine IndependentSimpleHigh-Level LanguagePopul 5 min read History of C++The C++ language is an object-oriented programming language & is a combination of both low-level & high-level language - a Middle-Level Language. The programming language was created, designed & developed by a Danish Computer Scientist - Bjarne Stroustrup at Bell Telephone Laboratories ( 7 min read Interesting Facts about C++C++ is a general-purpose, object-oriented programming language. It supports generic programming and low-level memory manipulation. 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These two ways are generally differentiated by the type of values passed to them as parameters.The following table lists the differences between the call-by-value and call-by-reference methods of parameter passing.Call By Valu 4 min read Default Arguments in C++A default argument is a value provided for a parameter in a function declaration that is automatically assigned by the compiler if no value is provided for those parameters in function call. If the value is passed for it, the default value is overwritten by the passed value.Example:C++#include <i 5 min read Inline Functions in C++In C++, inline functions provide a way to optimize the performance of the program by reducing the overhead related to a function call. When a function is specified as inline the whole code of the inline function is inserted or substituted at the point of its call during the compilation instead of us 6 min read Lambda Expression in C++C++ 11 introduced lambda expressions to allow inline functions which can be used for short snippets of code that are not going to be reused. Therefore, they do not require a name. They are mostly used in STL algorithms as callback functions.Example:C++#include <iostream> using namespace std; i 4 min read C++ Pointers and ReferencesPointers and References in C++In C++ pointers and references both are mechanisms used to deal with memory, memory address, and data in a program. Pointers are used to store the memory address of another variable whereas references are used to create an alias for an already existing variable. Pointers in C++ Pointers in C++ are a 5 min read C++ PointersA pointer is a special variable that holds the memory address of another variable, rather than storing a direct value itself. Pointers allow programs to access and manipulate data in memory efficiently, making them a key feature for system-level programming and dynamic memory management. When we acc 8 min read Dangling, Void , Null and Wild Pointers in CIn C programming pointers are used to manipulate memory addresses, to store the address of some variable or memory location. But certain situations and characteristics related to pointers become challenging in terms of memory safety and program behavior these include Dangling (when pointing to deall 6 min read Applications of Pointers in CPointers in C are variables that are used to store the memory address of another variable. Pointers allow us to efficiently manage the memory and hence optimize our program. In this article, we will discuss some of the major applications of pointers in C. Prerequisite: Pointers in C. C Pointers Appl 4 min read Understanding nullptr in C++Consider the following C++ program that shows problem with NULL (need of nullptr) CPP // C++ program to demonstrate problem with NULL #include <bits/stdc++.h> using namespace std; // function with integer argument void fun(int N) { cout << "fun(int)"; return;} // Overloaded fun 3 min read References in C++In C++, a reference works as an alias for an existing variable, providing an alternative name for it and allowing you to work with the original data directly.Example:C++#include <iostream> using namespace std; int main() { int x = 10; // ref is a reference to x. int& ref = x; // printing v 5 min read Can References Refer to Invalid Location in C++?Reference Variables: You can create a second name for a variable in C++, which you can use to read or edit the original data contained in that variable. While this may not sound appealing at first, declaring a reference and assigning it a variable allows you to treat the reference as if it were the 2 min read Pointers vs References in C++Prerequisite: Pointers, References C and C++ support pointers, which is different from most other programming languages such as Java, Python, Ruby, Perl and PHP as they only support references. But interestingly, C++, along with pointers, also supports references. On the surface, both references and 5 min read Passing By Pointer vs Passing By Reference in C++In C++, we can pass parameters to a function either by pointers or by reference. In both cases, we get the same result. So, what is the difference between Passing by Pointer and Passing by Reference in C++?Let's first understand what Passing by Pointer and Passing by Reference in C++ mean:Passing by 5 min read When do we pass arguments by pointer?In C, the pass-by pointer method allows users to pass the address of an argument to the function instead of the actual value. This allows programmers to change the actual data from the function and also improve the performance of the program. In C, variables are passed by pointer in the following ca 5 min read Like