C++ Variable Types


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:

There are following basic types of variable in C++

Type Description
bool Stores either value true or false.
char Typically a single octet(one byte). This is an integer type.
int The most natural size of integer for the machine.
float A single-precision floating point value.
double A double-precision floating point value.
void Represents the absence of type.
wchar_t A wide character type.

C++ also allows to define various other types of variables, which we will cover in subsequent chapters like Enumeration, Pointer, Array, Reference, Data structures, and Classes.


Variable Definition in C++

A variable definition means to tell the compiler where and how much to create the storage for the variable.

type variable_list;

Here, type must be a valid C++ data type including char, w_char, int, float, double, bool or any user-defined object, etc., and variable_list may consist of one or more identifier names separated by commas. Some valid declarations are shown here:

int i, j, k;
char c, ch;
float f, salary;
double d;

The line int i, j, k; both declares and defines the variables i, j and k; which instructs the compiler to create variables named i, j and k of type int.

Variables can be initialized (assigned an initial value) in their declaration. The initializer consists of an (=)equal sign followed by a constant expression as follows:

type variable_name = value;

Example

externint d =3, f =5;  // declaration of d and f. 
int d =3, f =5;  // definition and initializing d and f.
byte z =22;  // definition and initializes z. 
char x ='x';  // the variable x has the value 'x'.

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