letters | a,b,c,d,....z |
digits | 0,1,2,...,9 |
special characters | +,-,*,/ , ( ), ;, ", $ |
Beyond the general form of a program, perhaps no other construct is as important
to a programming language as the assignment of a value to a variable. A
variable is a named memory location that may be assigned a value. Further the
value of a variable may be changed one or more times during the execution of a
program.