- Constants are
values that do not change inside
a computer program
- Symbolic constants are constant values
with a
name attached to them
For example: PI = 3.141592653589793238462643383279502884197...
- There is no C++ language construct
to define symbolic constants
- Instead, C++ uses the
C++ pre-processor's
#define construct to define
symbolic constants
Example:
#define PI 3.141592653589793238462643383279502884197 #define MAX 99999 double x; x = PI;
- Example Program:
(Demo above code)
- Prog file: click here
To see the "symbolic substitution", compile program with:
CC -P constant.Cand use an editor to look inside constant.i.
Look at the end of the file !
- Multi-line comments
in a C++ program can also be enclosed between the pairs of
"brackets":
/* ..... ..... ..... */ - In addition,
single-line comment
in a C++ program can be put after
the symbol // :
// .... comment ....
- Examples:
/* This is a comment in a C or C++ program */
/* * This is an another comment in a C * or C++ program */
// This is a comment in a C++ program // Each comment line must be preceeded by its own //