Array, Structure and Union

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];

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

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

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 .

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.

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 */

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; popo

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 popo

Array, Structure and Union Eg 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) popo

Array, Structure and Union Eg 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) popo