What is Structure ?

A structure is a user-defined compound data type which consists of data members related to a person or an item. It is referred to record in other programming languages.

Syntax :

struct student { int roll_no; char sname[30]; int total; };

Note : The structure definition ends with a semicolon ( ; ) after the closing brace.

Example :

/* Description: structure program to store students data */ #include<stdio.h> struct student{ int roll_no; char sname[20]; int total; } main() { struct student std[10]; int i,j,k; puts("How many students data you want to store?(max 9) :"); scanf("%d",&j); for(i=1;i<=j;i++) { printf("\nEnter No.%d student roll number : ",i); scanf("%d",&std[i].roll_no); printf("Enter No.%d student name : ",i); scanf("%s",&std[i].sname); printf("Enter No.%d student total number : ",i); scanf("%d",&std[i].total); } puts("\n------ DATA STORE COMPLETED ------"); for(i=1;i<=j;i++) { printf("\n\nStudent No.%d student roll number : %d",i,std[i].roll_no); printf("\nStudent No.%d student roll number : %s",i,std[i].sname); printf("\nStudent No.%d student total number : %d",i,std[i].total); } getch(); }

Output :

Structure Variables and Arrays :

Structure variables can be declared using the tag-name of the structure along with the keyword struct.

Syntax :

struct student { int roll_no; char sname[30]; int total; }; struct student x,y,z; struct student std[50];

It declares structure variables x, y and z and an array std with 50 elements.

Dot ( . ) Operator :

Dot (.) or period operator is used to access a data member in a structure variable or an array element. It has the following form :

structure_variables.data_member

Note : That the dot operator separates the structure variables or array and the data member.

Example :

x.roll_no - std[i].roll_no
x.sname - std[i].sname
x.total - std[i].total

sizeof() Of a structure :

sizeof() of a structure is equal to the total number of bytes occupied in RAM by various data members in the structure.

struct student { int roll_no; char sname[30]; int total; };

The size of this structure is equal to 24bytes ( 2bytes for int + 20bytes for char + 2bytes for int ). The sizeof() function is written as follows to print the size of the structure :

printf("%d",sizeof(struct student));