Primitive Data Types

Every variable in C++ needs a type, and the primitive (or "fundamental") types are the most basic kinds of data a variable can hold. They store a simple value directly in memory, which makes them fast and memory-efficient.

int quantity = 10;
double price = 4.99;
bool inStock = true;
char grade = 'A';

int stores whole numbers (no decimal point) and is the default choice for counting things. double stores decimal numbers and is the default choice for anything with a fractional part, like prices or measurements. bool can only ever be true or false, which makes it perfect for yes/no conditions. char stores exactly one character, written in single quotes like 'A' — never double quotes, which are reserved for std::string.

To store a single character like 'A', you use the ____ type, written with single quotes.

C++ also has smaller and larger whole-number types for when int isn't the right fit: short saves memory for small numbers, while long and long long are used for whole numbers bigger than int can reliably hold. float is a smaller, less precise alternative to double, using less memory but storing fewer accurate decimal digits.

long long population = 8000000000;
short smallNumber = 120;
float approxPi = 3.14f;

One quirk of C++: the exact size (in bytes) of a type like int or long is not fixed by the language the same way it is in some other languages — it can vary slightly between compilers and platforms, though int is virtually always at least 4 bytes on modern systems. If you ever need to be certain, the sizeof operator tells you the exact size in bytes on your current setup.

std::cout << sizeof(int) << std::endl; // commonly prints 4

In C++, a local variable's exact byte size for a type like int is guaranteed to be identical on every computer and compiler in existence.

Which primitive type would you use to store whether a light switch is on or off?