Notes:

Arrow Operator Vs. Dot Operator in C Programming Language:

Dot operator (.):
- is used to access members of a structure directly through a normal structure variable
- is used to access members of a union directly through a normal union variable

Arrow operator (->):
- is used to access members of a structure indirectly through a pointer variable
- is used to access members of a union indirectly through a pointer variable

Structure:
- Structure is a collection of logically related data elements of similar or different data type.
- To represent any real world entity in a C program, we take help of a structure.
Ex:
Mathematical Application – Point, Rectangle, Circle etc.
College Management System Application – Student, Faculty, Subject etc.

Syntax for defining a Structure:

// defining a structure
struct StructureName
{
data_type variableName1;
data_type variableName2;
…
data_type variableNameN;
};

EX: // defining a Student structure
struct Student
{
int rollnum;
char *name;
float marks;
};

Syntax for declaring a Structure variable:

// declaring a structure variable
struct StructureName structureVariableName;

EX:
struct Student student1;
struct Student student2;
….
struct Student studentN;

Syntax for declaring and initializing a Structure variable:

// declaring and initializing a structure variable
struct StructureName structureVariableName =
{value 1,value2, … valueN};

EX:
struct Student student1 =
{1,”Suresh”,76.5};
struct Student student2 =
{2,”Ramesh”,86.5};

Syntax for getting members of a Structure using Dot operator:

// getting member of a structure
structureVariableName.membername

EX:
printf(“%d\n”,student1.rollnum); // 1
printf(“%s\n”,student1.name); // Suresh
printf(“%f\n”,student1.marks); // 76.5

Syntax for setting members of a Structure using Dot operator:

// setting member of a structure
structureVariableName.membername = value;

EX:
student1.marks = 86.5;
student2.marks = 76.5;

Syntax for declaring and initializing a Pointer to a Structure:

// declaring and initializing a Pointer to a Structure
struct structureName *pointerVariableName = &structureVariableName;

EX:
struct Student *ptrToStudent1= &student1;

Syntax for getting members of a Structure using Arrow operator:

// getting member of a structure
pointerVariableName->membername

EX:
printf(“%d\n”, ptrToStudent1->rollnum); // 1
printf(“%s\n”, ptrToStudent1->name); // Suresh
printf(“%f\n”, ptrToStudent1->marks); // 86.5

Syntax for setting members of a Structure using Arrow operator:

// setting member of a structure
pointerVariableName->membername = value;

EX:
ptrToStudent1 ->marks = 76.5;
ptrToStudent2 ->marks = 86.5;

Example Code:

#include <stdio.h>

int main()
{
struct Student{
int rollnum;
char *name;
float marks;
};

struct Student student1 = {1, "Suresh", 76.5};
struct Student student2 = {2, "Ramesh",86.5};
struct Student *ptrToStudent1 = &student1;
struct Student *ptrToStudent2 = &student2;

printf("student1 rollnum=%d\n",student1.rollnum);
printf("student1 name=%s\n",student1.name);
printf("student1 marks=%f\n",student1.marks);

printf("student2 rollnum=%d\n",student2.rollnum);
printf("student2 name=%s\n",student2.name);
printf("student2 marks=%f\n",student2.marks);

student1.marks = 86.5;
student2.marks=76.5;

printf("student1 rollnum=%d\n",student1.rollnum);
printf("student1 name=%s\n",student1.name);
printf("student1 marks=%f\n",student1.marks);

printf("student2 rollnum=%d\n",student2.rollnum);
printf("student2 name=%s\n",student2.name);
printf("student2 marks=%f\n",student2.marks);

printf("student1 rollnum=%d\n",ptrToStudent1->rollnum);
printf("student1 name=%s\n",ptrToStudent1->name);
printf("student1 marks=%f\n",ptrToStudent1->marks);

printf("student2 rollnum=%d\n",ptrToStudent2->rollnum);
printf("student2 name=%s\n",ptrToStudent2->name);
printf("student2 marks=%f\n",ptrToStudent2->marks);

ptrToStudent1->marks = 76.5;
ptrToStudent2->marks = 86.5;

printf("student1 rollnum=%d\n",ptrToStudent1->rollnum);
printf("student1 name=%s\n",ptrToStudent1->name);
printf("student1 marks=%f\n",ptrToStudent1->marks);

printf("student2 rollnum=%d\n",ptrToStudent2->rollnum);
printf("student2 name=%s\n",ptrToStudent2->name);
printf("student2 marks=%f\n",ptrToStudent2->marks);

return 0;
}