Syntax Array declaration is:
char array _name[ size];

In an array each element (Memorty box) has a unique index number starting from 0 which is known as "subscript".

struct student
{
int exam no;
char name[50];
int marks[5];
};

Array is good to use.
Reasons:
(i) All 100 numbers are integer type.
(ii) Array index helps to access the numbers quickly.

Structure is a user-defined which has the combination of data items with different data types. This allows to group of variables of mixed data types together into a single unit. The structure provides a facility to store different data types as a part of the same logical element in one memory chunk adjacent to each other.

A string is defined as a sequence of characters where each character may be a letter, number or a symbol. Each element occupies one byte of memory. Every string is terminated by a null ('\0', ASCII code 0) character which must be appended at the end of the string.

A structure without a name/tag is called anonymous structure.
struct
{
long rollno;
int age;
float weight;
} student;
The student can be referred as reference name to the above structure and the elements can be accessed like student.rollno, student.age and student.weight .

struct structure_name {
type member_name1;
type mamber _name2;
} reference_name;
Example:
struct Student
{
long rollno;
int age;
float weight;
};

}
struct student
int exam_no, lang, eng, phy, chem, mat, csc, total;
char name [15];
}
int main()
{
students [20];
for (int i = 0; i <20; i++)
{
cout<<"\n Enter the exam number of student:"";
cin>> s[i].exam_no.;
cout << "\n Enter language names:";
ein>>s[i].lang;
cout<<"Enter name of the Student:"";
cin>>s[i].Name;
}
for (int i=0; i<20; i++)
{
if (s[i],name[0] == 's')
{
cout << "Exam number:" << s[i].name;
cout << "Student Exam number";
}
}
return 0;}

#include< iostream >
using namespace std;
int main()
{
char name[20];
cout << "Enter your name'' << endl;
cin.get(name,20);
cout << "Your name:" << name«endl;
return 0;
}
output:
Enter your name : xxxx xxxx
Your name: xxxx xxxx

"An array is a collection of variables of the same type that are referenced by a common name".
An array is also a derived datatype in C++.
There are different types of arrays used in C++. They are:
1. One-dimensional arrays
2. Two-dimensional arrays
3. Multi-dimensional arrays

Output:
First Student roll no: 1
name: Brown
phone no: 123443
Second Student roll no: 2
name: Sam
Phone no : 1234567822
Third Student roll no: 3
name :Addy
Phone no : 1234567844

#include< iostream >
using namespace std;
struct complex
{
float real;
float imag;
} complexNumber;
complex Number add Complex Number(complex,
complex);
int main()
{
complexNumber
c1,c2, temp;
char simag;
cout << "Enter the value of A and B where A+iB is first complex number'' << xendl;
cin >> c1.real >> c1.imag;
cout << "Enter the value of A and B where A+iB is second complex number'' << endl;
cin >> c2.real >> c2.imag
simag=(temp.imag>0)?'+' : '-';
temp.imag=(tem.imag>0) >? temp.imag :-temp.
img;
temp = addcomplexNumber( c1, c2);
cout << "sum=" << temp.real << temp.imag << "i";
return 0;
}
complex Number add Complex Numbers(Complex
c1, Complex c2)
{
complex t;
t.real = c1.real + c2.real;
t.imag = c1.imag + c2.imag;
return(t);
}

Call by value:
When a structure is passed as argument to a function using call by value method, any change made to the contents of the structure variable inside the function to which it is passed do not effect the structure variable used as an argument.
Consider this example:
#include< iostream >
useing namespace std;
struct Employee
{
char name[50];
int age;
float salary;
};
void printData(Employee); //Function declaration
int main()
{
Employee p;
cout << "Enter Full name:";
cin >> p.name;
cout << "Enter age:";
cin >> p.age;
cout << "Enter salary:"; .
cin >> p.salary,
//Function call with structure variable as
an argument
PrintData(P);
return ();
}
void printData(Employee q)
{
cout << "\nDisplaying Information. " << endl;
cout << "Name:" << q.name << endl;
cout << "Age:" << q.age << endl;
cout << '' Salary: " << q.salary:
}
Output:
Enter Full name: Kumar
Enter age: 55
Enter salary: 34233.4
Displaying Information.
Name: Kumar
Age: 55
Salary: 34233.4