Variables and Declarations in C++

Variables in C Plus Plus (C++):

A variable can be defined as “a quantity that varies during program execution”.

A variable is a symbol that represents a storage location in the computer’s memory. The information that is stored in that location is called the¬†value¬†of the variable. One common way for a variable to obtain a value is by an assignment. This has the syntax:

variable = expression

First, the expression is evaluated and then the resulting value is assigned to the variable. The equal sign “=” is the assignment operator in C++.

Declarations in C++:

A declaration associates a group of variables with a specific data-type. All variables must be declared before they can appear in executable statements.

A declaration consists of a data-type, followed by one or more variable names, ending with a semicolon.


int a, b, c;
float root1, root2;
char flag;

Here,a, b and c are declared to be integer variables, root1 and root2 are floating-point variables and flag is a char-type variables.

These declarations could also have been written as follows:

int a;
int b;
int c;
float rot1;
float root2;
char flag;

Initial values can be assigned to variables within a type-declaration. To do so, the declaration must consist of a data-type, followed by a variable name, an equal sign (=) and a constant of the appropriate type. A semicolon must appear at the end, as usual.


int c = 12;
char star = '*';
float sum = 0.;
double factor = 0.123458e-6;

Thus, in above example, c is an integer variable whose initial value is 12, star ia a char-type variable initially assigned the character “*”, sum is a floating-point variable whose initial value is 0. and factor is a double-precision variable whose initial value is 0.123458 x 10-6.

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