What are Data Structures in C and How to use them

When working in C, you have access to various fundamental data structures that facilitate the storage and management of data. These include:

1. Arrays:

   • A collection of variables of the same type stored in a contiguous block of memory.
   • Enables storing multiple values in a single variable with access via an index.

2. Structures:

   • Also known as "structs," structures permit the storage of different data types in a single entity.
   • Defined by creating a type definition and then declaring variables of that type.

3. Linked Lists:

   • A sequence of nodes, each holding a value and a pointer to the next node.
   • Efficient for frequent insertions or deletions of data.

4. Trees:

   • A hierarchical set of nodes where each node, except the root, has a single parent.
   • Useful for organizing data hierarchically, like a file system's directory structure.

5. Hash Tables:

   • Uses a hash function to map keys to indices in an array.
   • Facilitates quick and efficient storage and retrieval of data, suitable for implementing dictionaries.

Use of Struct in C

Structs provide a versatile way to organize data with various applications in C.

Example Code

#include <iostream>
using namespace std;

struct Point {
  int x;
  int y;
};

int main() {
  Point p;  // Declare a variable of type "struct Point"
  p.x = 10;  // Assign a value to the "x" field of the struct
  p.y = 20;  // Assign a value to the "y" field of the struct

  cout << "Point p is at (" << p.x << ", " << p.y << ")\n";  // Print the values of the fields

  return 0;
}

In this example, a struct named "Point" is defined with two integer fields, "x" and "y." A variable "p" of type "struct Point" is declared, values are assigned to its fields, and the field values are then printed.

Additional Uses of Structs in C

• Defining and Using Structs with Different Data Types:

  // Example with typedef
  typedef struct {
    char name[50];
    int age;
    float grade;
  } Student;
  

• Defining and Using Structs with Pointers:

  typedef struct {
    char name[50];
    int age;
    float grade;
  } Student;
  
  void printStudent(Student* s) {
    // Print the values of the fields using the arrow operator
    cout << "Student " << s->name << " is " << s->age << " years old and has a grade of " << s->grade << endl;
  }
  

• Comparing Structs:

  Point p1 = {1, 2};
  Point p2 = {3, 4};
  Point p3 = {1, 2};
  
  if (p1 == p2) {
    cout << "p1 and p2 are equal\n";
  } else {
    cout << "p1 and p2 are not equal\n";
  }
  
  if (p1 == p3) {
    cout << "p1 and p3 are equal\n";
  } else {
    cout << "p1 and p3 are not equal\n";
  }
  

• Sizing Structs:

  cout << "Size of struct Student: " << sizeof(Student) << " bytes\n";
  

• Using Structs with Functions:

  Student createStudent(char* name, int age, float grade) {
    Student s;
    strcpy(s.name, name);
    s.age = age;
    s.grade = grade;
    return s;
  }
  

• Using Structs with Arrays:

  Student students[3] = {
    {"Alice", 18, 90.0},
    {"Bob", 20, 85.0},
    {"Charlie", 22, 80.0}
  };
  
  for (int i = 0; i < 3; i++) {
    cout << "Student " << students[i].name << " is " << students[i].age << " years old and has a grade of " << students[i].grade << endl;
  }
  

These examples showcase the versatility of structs in C for handling different data structures and scenarios.