Structures and Unions in C Programming

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Structures and Unions in C Programming

Introduction:

Structures and unions in C provide a way to group variables of different data types into a single unit. This comprehensive guide aims to provide a thorough understanding of structures and unions, covering basics, syntax, member access, differences, and practical applications.

See Also – while Loop in C Programming

Structures and Unions in C Programming

Table of Contents:

  1. Foundations of Structures in C
  • Structure Definition and Purpose
  • Declaring and Initializing Structures
  • Accessing Structure Members
  1. Advanced Structure Concepts
  • Nested Structures
  • Arrays of Structures
  • Pointers to Structures
  1. Foundations of Unions in C
  • Union Definition and Purpose
  • Declaring and Initializing Unions
  • Accessing Union Members
  1. Differences Between Structures and Unions
  • Memory Allocation
  • Member Access and Usage
  • Use Cases and Considerations
  1. Practical Applications of Structures and Unions in C
  • Record Keeping and Data Organization
  • Managing Employee Information
  • Handling Variants with Unions

1. Foundations of Structures in C:

Structure Definition and Purpose:

// Structure Definition and Purpose
struct Person {
    char name[50];
    int age;
    float height;
};

Declaring and Initializing Structures:

// Declaring and Initializing Structures
struct Person person1;  // Declaration
struct Person person2 = {"Alice", 25, 5.8};  // Initialization

Accessing Structure Members:

// Accessing Structure Members
printf("Name: %s, Age: %d, Height: %.2f\n", person2.name, person2.age, person2.height);

2. Advanced Structure Concepts:

Nested Structures:

// Nested Structures
struct Address {
    char street[50];
    char city[30];
};

struct Employee {
    char name[50];
    int empID;
    struct Address address;
};

Arrays of Structures:

// Arrays of Structures
struct Point {
    int x;
    int y;
};

struct Point points[5];  // Array of structures
points[0].x = 1;
points[0].y = 2;

Pointers to Structures:

// Pointers to Structures
struct Student {
    char name[50];
    int rollNumber;
};

struct Student *studentPtr;  // Pointer to a structure
studentPtr = &student1;
printf("Student Name: %s\n", studentPtr->name);

3. Foundations of Unions in C:

Union Definition and Purpose:

// Union Definition and Purpose
union Variant {
    int integerValue;
    float floatValue;
    char stringValue[50];
};

Declaring and Initializing Unions:

// Declaring and Initializing Unions
union Variant value;  // Declaration
value.integerValue = 42;  // Initialization

Accessing Union Members:

// Accessing Union Members
printf("Integer Value: %d\n", value.integerValue);

4. Differences Between Structures and Unions:

Memory Allocation:

  • Structures allocate memory for each member separately.
  • Unions allocate memory for the largest member.

Member Access and Usage:

  • All members in a structure can be accessed independently.
  • Only one member of a union can be accessed at a time.

Use Cases and Considerations:

  • Use structures when multiple pieces of data need to be stored and accessed independently.
  • Use unions when only one piece of data needs to be used at a time, and there is a need to save memory.

5. Practical Applications of Structures and Unions in C:

Record Keeping and Data Organization:

// Record Keeping and Data Organization
struct Employee {
    char name[50];
    int empID;
    float salary;
};

struct Employee employees[100];  // Array of structures for employee records

Managing Employee Information:

// Managing Employee Information
struct Employee {
    char name[50];
    int empID;
    float salary;
};

struct Employee employee1 = {"Bob", 101, 50000.0};
struct Employee employee2 = {"Alice", 102, 60000.0};

Handling Variants with Unions:

// Handling Variants with Unions
union Variant {
    int integerValue;
    float floatValue;
    char stringValue[50];
};

union Variant value;
value.integerValue = 42;

// Later in the code
printf("Current Value: %d\n", value.integerValue);
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Mahesh Wabale
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