C Programming - C Structures

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C Programming - C Structures

C Structures

A structure in C is a user-defined data type that allows grouping variables of different types under a single name. It provides a convenient way of handling related data as a single entity and is widely used in programming for defining complex data models.

Defining a Structure

The struct keyword is used to define a structure in C.

Syntax:

struct StructureName {
    dataType member1;
    dataType member2;
    // Additional members
};

Example:

struct Point {
    int x;
    int y;
};

Declaring Structure Variables

Method 1: Separate Declaration

struct Point p1, p2; 

Method 2: Declaration with Definition

struct Point {
    int x;
    int y;
} p1, p2;

Accessing Structure Members

Use the dot (.) operator to access the members of a structure.

Example:

struct Point {
    int x;
    int y;
};

int main() {
    struct Point p1;
    p1.x = 10;
    p1.y = 20;

    printf("x = %d, y = %d\n", p1.x, p1.y);
    return 0;
}

Nested Structures

Structures can contain other structures as members.

Example:

struct Point {
    int x;
    int y;
};

struct Rectangle {
    struct Point topLeft;
    struct Point bottomRight;
};

int main() {
    struct Rectangle rect = {{0, 0}, {10, 10}};
    printf("Top Left: (%d, %d)\n", rect.topLeft.x, rect.topLeft.y);
    printf("Bottom Right: (%d, %d)\n", rect.bottomRight.x, rect.bottomRight.y);
    return 0;
}

Arrays of Structures

You can create an array of structures to store multiple records.

Example:

struct Point {
    int x;
    int y;
};

int main() {
    struct Point points[3] = {{0, 0}, {1, 1}, {2, 2}};

    for (int i = 0; i < 3; i++) {
        printf("Point %d: (%d, %d)\n", i + 1, points[i].x, points[i].y);
    }
    return 0;
}

Pointer to Structure

A structure pointer is used to access members using the arrow operator (->).

Example:

struct Point {
    int x;
    int y;
};

int main() {
    struct Point p1 = {10, 20};
    struct Point *ptr = &p1;

    printf("x = %d, y = %d\n", ptr->x, ptr->y);
    return 0;
}

Self-Referential Structures

A structure can have a pointer to another structure of the same type.

Example:

struct Node {
    int data;
    struct Node *next;
};

This is commonly used in data structures like linked lists.

Passing Structures to Functions

Structures can be passed to functions by value or by reference.

By Value:

void display(struct Point p) {
    printf("x = %d, y = %d\n", p.x, p.y);
}
 
int main() {
    struct Point p1 = {10, 20};
    display(p1);
    return 0;
}

By Reference:

void display(struct Point *p) { 
    printf("x = %d, y = %d\n", p->x, p->y); 
} 
 
int main() {
    struct Point p1 = {10, 20};
    display(&p1);
    return 0;
}

Advantages of Structures

• Allows grouping of related data.
• Supports data abstraction and encapsulation.
• Simplifies program organization.
• Facilitates the implementation of complex data models.

Limitations of Structures

• Cannot have member functions like classes in object-oriented programming.
• No direct support for data hiding.
• Limited to static memory allocation unless combined with pointers.

Conclusion

Structures are a foundational feature of the C language, enabling efficient and organized handling of complex data. They pave the way for implementing advanced data structures like arrays, linked lists, stacks, and queues.