How to access structure elements using Pointers in C#

26 Feb, 2019
Unlike C/C++, Structures in C# can have members that are methods, fields, indexers, operator methods, properties or events. The members can have access specifiers as public, private, and internal.Pointers are variables that store the addresses of the same type of variable i.e. an int pointer can store an address of an integer, a char pointer can store an address of a char and similarly for all other data types, fundamental or user-defined.
You can access a structure member using pointers, of type structure, in the following ways;
1) Using the arrow operator: If the members of the structure are public then you can directly access them using the arrow operator ( -> ). If they are private then you can define methods for accessing the values and use pointers to access the methods. The arrow operator can be used to access structure variables as well as methods.
Syntax:
PointerName->memberName;
Example:
// C# Program to show the use of // pointers to access struct membersusing System;  namespace GFG {  // Defining a struct Studentstruct Student{    // With members    // roll number and marks    public int rno;    public double marks;      // Constructor to initialize values    public Student(int r, double m)    {        rno = r;        marks = m;    }}; // end of struct Student  class Program {      // Main Method    static void Main(string[] args)    {        // unsafe so as to use pointers        unsafe        {            // Declaring two Student Variables            Student S1 = new Student(1, 95.0);            Student S2 = new Student(2, 79.5);              // Declaring two Student pointers            // and initializing them with addresses            // of S1 and S2            Student* S1_ptr = &S1;            Student* S2_ptr = &S2;              // Displaying details of Student using pointers            // Using  the arrow ( -> ) operator            Console.WriteLine("Details of Student 1");              Console.WriteLine("Roll Number: {0} Marks: {1}",                             S1_ptr -> rno, S1_ptr -> marks);              Console.WriteLine("Details of Student 2");            Console.WriteLine("Roll Number: {0} Marks: {1}",                            S2_ptr -> rno, S2_ptr -> marks);          } // end unsafe      } // end main  } // end class  }
Output:
2) Using Dereferencing operator: You can also access structure elements using the dereferencing operator on the pointer, which is using an asterisk to dereference the pointer and then using the dot operator to specify the structure element.
Syntax:
(*PointerName).MemberName;
Example:
// C# Program to illustrate the use // of dereferencing operatorusing System;  namespace GFG {  // Defining struct Employeestruct Employee{      // Elements Eid and Salary    // With properties get and set    public int Eid     {             get;        set;    }  public double Salary{    get;    set;}}; // Employee ends  class Program {      // Main Method    static void Main(string[] args)    {        // unsafe so as to use pointers        unsafe        {            // Declaring a variable of type Employee            Employee E1;              // Declaring pointer of type Employee            // initialized to point to E1            Employee* ptr = &E1;              // Accessing struct elements using            // dereferencing operator            // calls the set accessor            (*ptr).Eid = 1101;            (*ptr).Salary = 1000.00;              Console.WriteLine("Details of Employee");            // calls the get accessor            Console.WriteLine("Employee Id: {0}\nSalary: {1}",                                   (*ptr).Eid, (*ptr).Salary);          } // end unsafe      } // end Main  } // end class  }
Output:
Note: To compile unsafe code on Visual Studio (2012), Go to Project –> ProjectName Properties –> Build –> Check the “Allow unsafe code” box.
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