C++ Tutorial Index

C++ Tutorial C++ History C++ Installation C++ First Program C++ cin and cout C++ Data type C++ Variable C++ operator C++ Keywords

C++ Control Statements

C++ If C++ Nested if C++ If-else C++ If-else-if C++ Switch C++ Break C++ Continue C++ Goto C++ For loop C++ While loop C++ Do while loop

C++ Functions

C++ Call by Value C++ Call by Reference C++ Recursion Function C++ Inline function C++ Friend function

C++ Arrays

Single dimension array Two dimension array

C++ Strings

C++ Strings

C++ Inheritance

C++ Inheritance Single level Inheritance Multilevel Inheritance Multiple Inheritance Hierarchical Inheritance Hybrid Inheritance

C++ Polymorphism

C++ Polymorphism C++ Overloading C++ Overriding C++ Virtual Function

C++ Pointers

C++ Pointers C++ this pointer

C++ Exception Handling

C++ Exception Handling

C++ Constructors

C++ Constructors Default Constructor Parameterize Constructor Copy constructor Constructor Overloading Destructor

C++ File Handling

C++ File Handling C++ Writing to file C++ Reading file C++ Close file

Miscellaneous

C Vs C++ C++ Comments C++ Data Abstraction C++ Identifier C++ Memory Management C++ Storage Classes C++ Void Pointer C++ Array To Function C++ Expressions C++ Features C++ Interfaces C++ Encapsulation std::min in C++ External merge sort in C++ Remove duplicates from sorted array in C++ Precision of floating point numbers Using these functions floor(), ceil(), trunc(), round() and setprecision() in C++ C++ References C++ Friend Functions C++ Mutable keyword Unary Operators in C++ Initialize Array of objects with parameterized constructors in C++ Differences between #define & const in C/C++ C++ Program to Implement Shell Sort C++ Program to Implement Merge Sort Storage Classes in C Vector resize() in C++ Passing by Reference Vs. Passing by the pointer in C++ Free vs delete() in C++ goto statement in C and C++ C++ program to read string using cin.getline() C++ String Concatenation Heap Sort in C++ Swap numbers in C++ Input Iterators in C++ Fibonacci Series in C++ C ++ Program: Alphabet Triangle and Number Triangle C++ Program: Matrix Multiplication C++ Program to Print Fibonacci Triangle Stack in C++ Maps in C++ Queue in C++ C++ Bitset C++ Algorithms Priority Queue in C++ C++ Multimap C++ Deque Function Pointer in C++ Sizeof() Operators in C++ C++ array of Pointers free() Vs delete in C Timsort Implementation Using C++ CPP Templates C++ Aggregation C++ Enumeration C++ Math Functions C++ Object Class C++ Queue Initialize Vector in C++ Vector in C++ C++ STL Components Function overloading in C++ C++ Maximum Index Problem C++ find missing in the second array C++ Program to find the product array puzzle C++ Program To Find Largest Subarray With 0 Sum C++ Program To Move All Zeros To The End Of The Array C++ Program to find the element that occurs once C++ Program to find the largest number formed from an array Constructor Vs Destructor C++ Namespaces C++ OOPs Concept C++ Static C++ Structs C++ Try-Catch C++ User Defined Exceptions C++ Virtual Destructor C++ vs C# Malloc() and new in C++ Palindrome Number Program in C++ Snake Code in C++ Splitting a string in C++ Structure Vs Class in C++ Virtual Function Vs Pure Virtual Function C++ Bidirectional Iterators C++ Forward Iterators C++ Iterators C++ Output Iterators C++ Range-based For Loop Converting string into integer in C++ LCM Program in C++ Type conversion in C++ Add two numbers using the function in C++ Advantage and disadvantage friend function C++ Armstrong Number Program in C++ ATM machine program in C++ using functions Binary to Decimal in C++ Bit Manipulation in C++ C++ Constructor C++ Dijkstra Algorithm Using the Priority Queue C++ int into String C++ Signal Handling Decimal to Binary in C++ Decimal to Hexadecimal in C++ Decimal to Octal in C++ Factorial Program in C++ Function in C++ Hexadecimal to Decimal in C++ Octal to Decimal in C++ Reverse a Number in C++ Structure Vs Class in C++ C++ Forward Iterators C++ Output Iterators C++ Prime number program Char Array to String in C++ Constructor Overloading in C++ Default arguments in C++ Different Ways to Compare Strings in C++ Dynamic Binding in C++ Program to convert infix to postfix expression in C++ SET Data Structure in C++ Upcasting and Downcasting in C++ Reverse an Array in C++ Fast Input and Output in C++ Delete Operator in C++ Copy elision in C++ C++ Date and Time C++ Bitwise XOR Operator Array of sets in C++ Binary Operator Overloading in C++ Binary Search in C++ Implementing the sets without C++ STL containers Scope Resolution Operator in C++ Smart pointers in C++ Types of polymorphism in C++ Exception Handling in C++ vs Java Const Keyword in C++ Type Casting in C++ Static keyword in C++ vs Java Inheritance in C++ vs Java How to concatenate two strings in C++ Programs to Print Pyramid Patterns in C++ swap() function in C++ Structure of C++ Program Stringstream in C++ and its applications rand() and srand() in C / C++ C++ Ternary Operator C++ Scope of Variables While Loop Examples in C++ Star pattern in C++ using For Loops For Loop Examples in C++ Do-While Loop Examples in C++ Top 5 IDEs for C++ That You Should Try Once Assertions in C/C++ C++ Convert Int to String Continue in C++ While loop Diamond Pattern in C++ using For Loop How to Reverse a String in C++ using Do-While Loop How to Reverse a String in C++ using For Loop How to Reverse a String in C++ using While Loop Infinite loop in C++ Loops in C++

C++ Structs

We frequently encounter scenarios in which we must store a bunch of data, whether of comparable or dissimilar data kinds. Arrays are used to hold a group of data of comparable data kinds at contiguous memory regions in C++.

Structures in C++, unlike Arrays, are user-defined data types that are used to hold groups of objects of dissimilar data types.

In C++, what is a Struct?

A Struct is a data structure in C++ that may be used to hold pieces of several data types together. A C++ structure is a programmer-defined data type. The structure provides a data type that may be used to aggregate objects of various data types into an individual data type.

Example:

Consider storing information about someone, such as their name, standard and roll number. To keep the data independently, you may construct variables such as name, standard, and roll_num.

Although, we would most probably be needing to keep the same data for a greater amount of people in the future. It indicates that distinct variables will be established for different people. Name1, standard1, roll_num1, and so forth. This is a compilation of all linked data under one name i.e. Info which is a struct. Hence, it is preferable to construct a struct to avoid this.

When should a Structure Be Used?

Here are a few reasons why you should use structure in C++ :

  • When we want to keep elements of many data types in one data type, we use a struct.
  • Structs in C++ are value types rather than reference types. If we don't plan to change our data after it's created, we use a struct.

How to initialize a struct in C++?

The keyword struct, accompanied by an identifier, is used to build a C++ structure. The identifier will become the struct's name. The syntax for creating a C++ struct is as follows:

Syntax:

struct struct_names  
{  
     // structure data members
}   

The struct keyword is used in the above syntax. The struct_names is the structure's name. Curly brackets are used to add the struct elements. These distinct individuals  more often be from various different data categories.

Example:

struct Student  
{  
    char name[40];  
     int standard;  
     int roll_num;  
} 

Explanation:

Student is a three-membered structure in the example above. Name, standard and roll_num are among the members. This structure is built with char data type for name, integer datatype for standard and integer datatype for roll_num also. Memory will be allocated only after a variable will be appended to the struct.

Creating instances for a struct:

We generated a struct called Student in the preceding example. We can make a struct variable like this:

Student st;

The struct variable st is of the type Student. This variable can be used to access the struct's members.

Accessing the members of a struct:

We utilise the struct instance and the dot “.” operator to access the element of the struct. The member access operator is represented by a period between the name of the structure variable and the name of the structure member we want to access. To define variables of the structure type, we'd use the term struct. To get the member standard of struct Student :

Example:

st.standard = 8;

Explanation:

We used the struct's instance st, to get the member standard of struct Student. After that, we changed the member's standard to 8.

Example:

#include <iostream>    
using namespace std;
struct Student
{
	int standard;
	int roll_num;
};
int main(void) {
	struct Student st;
	st.standard = 8;
	st.roll_num = 21;
	cout << "Student’s standard: " << st.standard << endl;
	cout << "Student’s roll number: " << st.roll_num << endl;


	return 0;
}

Output:

Student’s standard: 8
Student’s roll number: 21

Explanation:

In the above example, we created a struct Student with two struct members of integer type namely standard and roll_num. Then in the main() function we created an instance st of struct Student. Using that instance, we provided values for standard and roll_num and they were printed as required.

Structure pointer:

A pointer that refers to a structure can be created. It's analogous to how pointers to native data types like as int, float, double, and so on are produced. In C++, a pointer is used to hold a memory address. Members are accessed using the arrow (->) operator rather than the dot (.) operator when we have a pointer pointing to a structure.

Example:

#include <iostream>
using namespace std;


struct Lengths
{
	int mtrs;
	float ctmtrs;
};


int main()
{
	Lengths *ptr, z;


	ptr = &z;


	cout << "Enter length in meters: ";
	cin >> (*ptr).mtrs;
	cout << "Enter length in centimeters: ";
	cin >> (*ptr).ctmtrs;
	cout << "Length = " << (*ptr).mtrs << " meters " << (*ptr).ctmtrs << " centimeters";


	return 0;
}

Output:

Enter length in meters: 10
Enter length in centimeters: 34
Length = 10 meters 34 centimeters

Explanation:

In the above example, we created a struct Lengths with two struct members of integer type namely mtrs and ctmtrs. Then in the main() function we created a pointer variable *ptr and a normal variable z of type Lengths whose address is stored in the pointer variable. Using that instance, we asked values for mtrs and ctmtrs and they were printed as required.

Passing Struct as function argument:

A struct can be sent as an argument to a function. This is proceeded in the same way as the passing of a standard argument. A function can also be supplied struct variables. When you do need to present the data of struct members, this is an excellent example.

Example:

#include<iostream>
using namespace std;


struct Student
{
	int standard;
	int roll_num;
};


void func(struct Student st);


int main()
{
	struct Student st;


	st.standard = 9;
	st.roll_num = 24;


	func(st);
	return 0;
}
void func(struct Student st)
{
	cout << "Student’s standard: " << st.standard << endl;
	cout << "Student’s roll number: " << st.roll_num << endl;
}

Output:

Student’s standard: 9
Student’s roll number: 24

Explanation:

In the above example, we created a struct Student with two struct members of integer type namely standard and roll_num. Then created a function func() that takes the instance st of struct Student as the argument. Then in the main() function we created an instance st of struct Student. When that function func() will be called the instance of the struct st will be passed as an argument and using that instance, we provided values for standard and roll_num and they were printed as required.

Drawbacks of C++ Structure:

C++ Structures have the following drawbacks:

  • Built-in data types cannot be used with the struct data type.
  • On structural variables, operators like +, -, and others are not allowed.
  • Data concealing is not possible with structures. Any function, regardless of its scope, can access the members of a structure.
  • Static members cannot be defined within the structural body.
  • Constructors cannot be built inside a struct.

Differences between a Struct and a class:

ParametersStructClass
DefinitionA structure is a collection of variables of different data kinds with the same name.A class in C++ is a single structure that contains a collection of linked variables and functions.
Declared asstruct structures_name{ type structs_member1; type struct_member2; . type struct_memberN; };  class class_names{ data members;   members func; };  
GeneralEvery member is set to 'public' when no access specifier is supplied.Every member is set to 'private' if no access specifier is given.
ObjectiveData classification.Further inheritance and data abstraction.
InstancesThe 'structure variable' is the name for a structure instance.The term 'object' refers to a class instance.
Used forIt's for tiny bits of information.It stores a large quantity of data.
Memory AllocationThe stack is used to allocate memory.The heap is where memory is allocated.
Constructor and DestructorIt's possible that it only has a parameterized constructor.It might include any number of both, constructors and destructors.
ReusabilityNot reusableFully reusable
Initialization of members variablesNot allowed.Allowed.
Default empty size0 Bytes1 Byte
Garbage collectionSince it employs pass by value, this isn't feasible.Since it utilises pass by reference, it's possible.
Memory managementPoorEffective

Conclusion:

  • A struct is a data structure for storing data pieces of various kinds.
  • A struct contains data elements of diverse kinds, while an array contains data items of the same type.
  • When the data pieces are not supposed to change value, a struct must be utilised.
  • The dot (.) operator is used to access the data members of a struct.
  • We must first build a struct instance.
  • The struct keyword is used to build a C++ struct.
  • Pointers referring to structs are constructed in the same way that pointers pointing to normal types are.
  • A struct could be supplied to a function as an argument in the same manner that regular functions are.



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