Answer & Explanation
A variable provides us with named storage that our programs can manipulate. Each variable in C++ has a specific type, which determines the size and layout of the variable's memory the range of values that can be stored within that memory and the set of operations that can be applied to the variable.
The name of a variable can be composed of letters, digits, and the underscore character. It must begin with either a letter or an underscore. Upper and lowercase letters are distinct because C++ is case-sensitive −
Basic types of variables:
Stores either value true or false.
Typically a single octet (one byte). This is an integer type.
The most natural size of an integer for the machine.
A single-precision floating point value.
A double-precision floating point value.
Represents the absence of type.
A wide character type.