2.6 SYMBOLIC CONSTANTS

A constant is defined as follows:

#define SYMBOLIC_NAME value_of_constant

e.g.

#define PASS_MARK 50

#define MAX 100

#define PI 3.14159

Symbolic names are sometimes called constant identifiers.

The following rules apply to a #define statement:

1)      Symbolic names have the same form as variable names. (Symbolic names are written in CAPITALS to visually distinguish them from the normal variable names, which are written in lowercase letters. This is only a convention, not a rule.)

2)      No blank spaces between the pound sign ‘#’ and the word ‘define’ is permitted.

3)      ‘#’ must be the first character in the line.

4)      A blank space is required between #define and symbolic name and between symbolic name and the constant.

5)      #define statements must not end with a semicolon.

6)      After definition, the symbolic name should not be assigned any other value within the program by using an assignment statement. e.g. MAX = 500; is illegal.

7)      Symbolic names are NOT declared doe data types. Its data type depends on the type of constant.