C++ Modified Data Types List

auto: Deduces the type of a variable from its initializer.
decltype: Inspects the declared type of an entity or the type and value category of an expression.
const: Specifies that an object is not modifiable.
volatile: Specifies that an object can be modified by something beyond the control of the program.
mutable: Allows a non-static data member to be modified even if the containing object is declared as const.
register: Suggests to the compiler that a variable should be stored in a register, if possible.
static: Specifies that a variable, function, or data member is shared among all instances of a class or object.
extern: Declares that a variable or function is defined in another source file or library.
thread_local: Specifies that a variable has thread-local storage duration.

I hope this helps! If you have any further questions, feel free to ask.