1. Array, Structure and Union

2. Array, Structure and Union
Group of related data items which shares a common name
More than one items, with same name and same data type
If we need more variables of same type, then we can use array
An array can be declared as
int a[10];
a integer array with 10 elements
data type array name [size];

3. Array, Structure and Union
Each elements in the array can access using its relative position, called index of the array or subscript of the array
Index of first element is 0, second element is 1 and so on
int a[10];
Index a[0] a[1] a[2] a[3] a[4] a[5] a[6] a[7] a[8] a[9] 10 20 30 40 50 60 70 80 90
100

4. Array, Structure and Union
Each elements in the array can be access using a loop
Reading an array
for(i=0;i<n;i++) {
scanf(“%d”,&a[i]); }
Printing an array
printf(“%d “,a[i]);
Where nsize of the array

5. Array, Structure and Union
A structure is a collection of one or more variables, possibly of different types, grouped together under a single name
Grouping logically related data, and giving this set of variables a higher-level name .

6. Array, Structure and Union
A structure is defined by the keyword struct followed by a set of variables enclosed in braces.
Consider the following structure to represent a person’s details.
struct Personnel {
char name[100];
int age;
double height; };
The variables name, age and height are called members of the structure type Personnel.

7. Array, Structure and Union
There are two ways to define variables of a particular structure type.
Declare them at the structure definition.
struct Personnel {
char name[100];
int age;
double height;
} p1, p2, p3; /* Define 3 variables */
Define the variables at some point after the structure definition.
struct Personnel p1, p2, p3; /* Define 3 variables */

8. Array, Structure and Union
Union is same as the structure
Like structure, union also contains members of different data type
Union can be declared using the keyword union
Syntax: union unionname{
member 1;
member 2; };
Like structure a union variable can be declare
Syn: union unionname variable list;
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9. Array, Structure and Union
The memory space occupy for a union variable is the size of largest member
In structure each members has its own memory locations
In union all members shares a common memory location
In structure we can access all members at a time
In union we can access only one member at a time
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10. Array, Structure and UnionEg
Stuct check {
int age;
char name[5];
}s;
The memory space of struct variable s=sum of size of all members
Ie sizeof(age)+sizeof(name)
=> 2+5 = 7 bytes
The structure variable has separate memory locations for each members
Can access all members at a time
age (2 bytes)
name (5 bytes)
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11. Array, Structure and UnionEg
union check {
int age;
char name[5];
}u;
The memory space of union variable s=size of largest members
Ie sizeof(name)
=> 5 = 5 bytes
The union variable has only one memory locations for all members
Can access only one member at a time
name (5 bytes)
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