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
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;
a, b and
c are declared to be integer variables,
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.