Structures in C++ allow grouping of related data types into one data type. A structure defines members of different data types within curly braces. Structure variables can be declared and members accessed using dot operator. Arrays of structures can be used to store multiple structure objects. References in C++ provide an alias for an existing variable and any changes made using reference are reflected in original variable. Function parameters passed by value cannot swap values but passing by reference allows swapping of values.

1. Computer Programming -II
Instructor:
Dr. Satyavir Singh
Assistant Professor

2. C++ Structures (struct)
• C++ Structures
• Structures (also called structs) are a way to group
several related variables into one place. Each variable
in the structure is known as a member of the
structure.
• Unlike an array, a structure can contain many
different data types (int, string, bool, etc.).
• Create a Structure
• To create a structure, use the struct keyword and
declare each of its members inside curly braces.
• struct name { // Structure declaration
int myNum; // Member (int variable)
string myString; // Member (string variable)
} myStructure; // Structure variable

3. Access Structure Members
#include <iostream>
#include <string>
using namespace std;
int main() {
struct {
int myNum;
string myString;
} myStructure;
myStructure.myNum = 1;
myStructure.myString = "Hello World!";
cout << myStructure.myNum << "n";
cout << myStructure.myString << "n";
return 0;
}

4. One Structure in Multiple Variables
• struct {
int myNum;
string myString;
} myStruct1, myStruct2, myStruct3; // Multiple
structure variables separated with commas

5. #include <iostream>
#include <string>
using namespace std;
int main() {
struct book {
string name;
float price;
int pages;
} b1, b2;
b1.name="C";
b1.price=130.00;
b1.pages=550;
b2.name="C++";
b2.price=140.00;
b2.pages=650;
cout<<"book b1 detailsn"<<b1.name<<"t"<<b1.price<<"t"<<b1.pages<<"n";
cout<<"book b2 detailsn"<<b2.name<<"t"<<b2.price<<"t"<<b2.pages<<"n";
return 0;
}
Struct book

6. #include <iostream>
#include <string>
using namespace std;
int main() {
struct myCar{
string brand;
string model;
int year;
} myCar1, myCar2; // We can add variables by separating them with a comma here
// Put data into the first structure
myCar1.brand = "BMW";
myCar1.model = "X5";
myCar1.year = 1999;
// Put data into the second structure
myCar2.brand = "Ford";
myCar2.model = “Escort";
myCar2.year = 1969;
// Print the structure members
cout << myCar1.brand << " " << myCar1.model << " " << myCar1.year << "n";
cout << myCar2.brand << " " << myCar2.model << " " << myCar2.year << "n";
return 0;
}
Struct myCar

7. Array of Structures
#include <iostream>
#include <string>
using namespace std;
int main() {
struct book {
string name;
float price;
int pages;
} ;
book b[100];
for(int i=0;i<100;i++)
{
cout<<“Enter the books name, price and pages:n”;
cin>>b[i].name>>b[i].price>>b[i].pages;
}
cout<<“Book details are:”;
for(int i=0;i<100;i++)
{
cout<<b[i].name<<“n”<<b[i].price<<“n”<<b[i].pages<<“n”;
}
return 0;
}

8. C++ References
Creating References
• A reference variable is a "reference" to an existing variable, and it is created with
the & operator:
string food = "Pizza"; // food variable
string &meal = food;
Now, we can use either the variable name food or the reference name meal to refer to
the food variable:
#include <iostream>
#include <string>
using namespace std;
int main() {
string food = "Pizza";
string &meal = food;
cout << food << "n";
cout << meal << "n";
return 0;
}
Output:
Pizza
Pizza

9. C++ References
• A reference variable provide an alias (alternative
name) for a previously defined variable.
Example
float total=100;
float &sum=total;
cout<<total; Output: 100
cout<<sum ; Output: 100
total=total+10;
cout<<total; Output: 110
cout<<sum; Output: 110

10. #include<iostream>
using namespace std;
void swap(int ,int );
int main()
{
int a,b;
cout<<"Enter the two numbers to swap";
cin>>a>>b;
cout<<"nAfter swapping of two numbers:";
swap(a,b);
cout<<a<<"t"<<b;
return 0;
}
void swap(int a, int b)
{
int temp;
temp=a;
a=b;
b=temp;
}
Swapping of two numbers using call by value

11. Swapping of two numbers using call by reference
#include <iostream>
using namespace std;
int main() {
int a=5, b=10;
cout << “Before swapping:t” <<a<<“t”<<b;
swap(a,b);
cout << “After swapping:t” <<a<<“t”<<b;
return 0;
}
void swap(int &num1, int &num2)
{ int temp;
temp=num1;
num1=num2;
num2=temp;
}

12. #include<iostream>
using namespace std;
void swap(int ,int );
int main()
{
int a,b;
cout<<"Enter the Two Numbers to Swap: ";
cin>>a>>b;
swap(a,b);
return 0;
}
void swap(int a, int b)
{
int temp;
temp=a;
a=b;
b=temp;
cout<<"nAfter Swapping of Two Numbers:";
cout<<a<<"t"<<b;
}
Swapping of two numbers using call by value