Data Types in C++

In C++, data types are used to categorize different types of data that a program can process. They are essential for determining the type of value a variable can hold and how much memory space it will occupy. Some basic data types in C++ include integers, floating-point numbers, characters, and booleans.

Fundamental Data Types

Integer (int)

Integers are whole numbers that can store both positive and negative values. The size of int depends on the system architecture (usually 4 bytes).

Example:

int num = 42;

There are variants of int that can hold different ranges of numbers:

short (short int): Smaller range than int.
long (long int): Larger range than int.
long long (long long int): Even larger range than long int.

Floating-Point (float, double)

Floating-point types represent real numbers, i.e., numbers with a decimal point. There are two main floating-point types:

float: Provides single-precision floating-point numbers. It typically occupies 4 bytes of memory.

Example:

float pi = 3.14f;

double: Provides double-precision floating-point numbers. It consumes more memory (usually 8 bytes) but has a higher precision than float.

Example:

double pi_high_precision = 3.1415926535;

Character (char)

Characters represent a single character, such as a letter, digit, or symbol. They are stored using the ASCII value of the symbol and typically occupy 1 byte of memory.

Example:

char letter = 'A';

Boolean (bool)

Booleans represent logical values: true or false. They usually occupy 1 byte of memory.

Example:

bool is_cpp_great = true;

Derived Data Types

Derived data types are types that are derived from fundamental data types. Some examples include:

Arrays

Arrays are used to store multiple values of the same data type in consecutive memory locations.

Example:

int numbers[5] = {1, 2, 3, 4, 5};

Pointers

Pointers are used to store the memory address of a variable.

Example:

int num = 42;
int* pNum = &num;

References

References are an alternative way to share memory locations between variables, allowing you to create an alias for another variable.

Example:

int num = 42;
int& numRef = num;

User-Defined Data Types

User-defined data types are types that are defined by the programmer, such as structures, classes, and unions.

Structures (struct)

Structures are used to group variables of different data types together under a single name.

Example:

struct Person {
    string name;
    int age;
    float height;
};

Person p1 = {"John Doe", 30, 5.9};

Classes (class)

Classes are similar to structures, but they can also have member functions and access specifiers.

Example:

class Person {
  public:
    string name;
    int age;

    void printInfo() { cout << "Name: " << name << ", Age: " << age << endl; };
};

Person p1;
p1.name = "John Doe";
p1.age = 30;

Unions (union)

Unions are used to store different data types in the same memory location.

Example:

union Data {
    int num;
    char letter;
    float decimal;
};

Data myData;
myData.num = 42;

Programming Notes