In C, data types can be broadly categorized into three main types:

1. Predefined Data Types

These are the fundamental data types built into the C language.

• Integer Types:
  • int: Represents integer values. Example: int age = 25;
  • short: Represents short integer values. Example: short temp = -5;
  • long: Represents long integer values. Example: long population = 100000L;
  • long long: Represents very large integers. Example: long long bigNum = 9876543210LL;
• Floating-Point Types:
  • float: Represents single-precision floating-point numbers. Example: float height = 5.9f;
  • double: Represents double-precision floating-point numbers. Example: double pi = 3.14159;
  • long double: Represents extended precision floating-point numbers. Example: long double bigNum = 3.14159265358979323846L;
• Character Type:
  • char: Represents a single character. Example: char initial = 'A';

2. Derived Data Types

• array, pointers, function

3. Derived Data Types

• Structures (struct)

Structures allow you to group variables of different types together. This is useful for representing a record or an entity

struct Person {
char name[50];
int age;
float height;
};

// Usage
struct Person person1;
strcpy(person1.name, “Alice”);
person1.age = 30;
person1.height = 5.5;

• Unions (union)

  Unions are similar to structures but allow you to store different data types in the same memory location. Only one member can hold a value at any given time.

union Data {
int intValue;
float floatValue;
char charValue;
};

// Usage
union Data data;
data.intValue = 10; // Only intValue holds a valid value at this point

• Enumerations (enum)

  Enumerations define a variable that can take a set of named integer constants. This improves code readability and maintainability.

enum Day {Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday};

// Usage
enum Day today;
today = Wednesday;

• Typedef

  typedef is a keyword that allows you to create an alias for existing data types. This can simplify code and improve clarity.

typedef struct {
char name[50];
int age;
} Person;

// Usage
Person person1; // Now you can use Person instead of struct Person