CSCE 2050
Programming Assignment 5
Fall 2006
Due Date: Friday, Dec. 8
Requirements [Lists, Stacks, Symbol Table, and Trees.] The diļ¬erence between this assignment and
the last is in the speciļ¬cations section. Read from the input stream a sequence of (inļ¬x) arithmetic
statements composed of
ā¢Nonnegative integers: 0, 1, 2, etc.
ā¢Variables: a, b, c, ..., z
ā¢Parentheses: ( and )
ā¢Arithmetic operators: +, -, *, /, ^,and=
A semicolon will be used to denote the end of each statement.
Statements will be in the form of assignment statements, that is, a variable (the left variable) followed
by ā=ā followed by an arithmetic expression. Translate the statement to an internal code, then evaluate
the statement using the postļ¬x. The evaluation of a subexpression consisting in part of a left variable
will be to update the value of the left variable in the symbol table. When the end of the list of
statements is encountered (i.e., a statement consisting only of a semi-colon) print the values of each
variable used in the the sequence of statements.
Specifications The input should appear as follows:
Please enter a sequence of arithmetic statements
a=2;
b=4^a-6;
c=3*a+b;
;
The output should appear as follows:
Variable Value
a2
b10
c16
The symbols must appear in alphabetical order in the output list. Please note also the following issues
that your code must take into account.
ā¢If the expression does not have balanced parentheses, an error message should be printed, the
stack(s) should be made empty, and the program proceed to the next statement.
ā¢If a statement does not have a left variable, do the same.
ā¢Note that variables may have negative values as via the statement: a=0ā2.
ā¢All arithmetic is integer arithmetic so 2^a would be zero for all negative values of a. You do not
need to check for this. It is a natural outcome of integer arithmetic.
ā¢Note that it is possible for a variable to appear to the right of equal (=) that has not been assigned
a value. This is also an error.
