Structures in C

Introduction

A structure in C is a user-defined data type that allows storing multiple variables of different data types under a single name. Structures are useful for organizing complex data like student records, employee details, or product information.

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Key Points

1. Structure Declaration

• Syntax: struct StructureName { dataType member1; dataType member2; ... };
• Example: struct Student { int id; char name[20]; float marks; };

2. Structure Variables

• Declare variables of the structure type: struct Student s1, s2;

3. Accessing Members

• Use the dot operator (.) to access members: s1.id = 101; strcpy(s1.name, "Alice"); s1.marks = 85.5;

4. Nested Structures

• A structure can contain another structure: struct Date { int day, month, year; }; struct Student { int id; char name[20]; struct Date dob; };

5. Arrays of Structures

• Store multiple records in an array of structures: struct Student students[5];

6. Pointers to Structures

• Use pointers with the arrow operator (->): struct Student *ptr = &s1; printf("%d", ptr->id);

7. Advantages

• Organizes complex data in one unit
• Easier data management
• Supports modular programming

8. Limitations

• Cannot have operations directly on structures
• Memory allocation is static unless combined with pointers

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Example Code

#include <stdio.h>
#include <string.h>

struct Student {
    int id;
    char name[20];
    float marks;
};

int main() {
    struct Student s1;
    s1.id = 101;
    strcpy(s1.name, "Alice");
    s1.marks = 88.5;

    printf("ID: %d\nName: %s\nMarks: %.2f\n", s1.id, s1.name, s1.marks);
    return 0;
}