program讲解 、辅导 c++，Java程序设计
Program Specification:
Build a hash table using chaining as the collision resolution technique using a linked list. Insertions into
the hash table will correspond to declarations of variables and values in a program, searches will be
requests for the value of a variable. Some variables will be local and have a narrow scope while some
variables will be global.
The program will take input from a file OR console via getline, another program written in the omnipotent
programming language BORG (Bionicly Omnipotent Resistance Grinders) and generate output from this
program.
The BORG language has the following commands (keywords):
1. START-FINISH blocks. Indicating different scopes.
2. COM - Single line comments: Text should be ignored if on the same line
3. VAR varName – Variable Declaration, adds “varName” to the hash table.
4. variable = expression – Assignment statements, ie GEORGE = 122. Find GEORGE in the hash table
and assign 122 to it.
5. ++ - increment operator, syntax: VARIABLE ++
6. -- - decrement operator, syntax: VARIABLE --
7. expressions, expressions are limited to unary and binary arithmetic, or variable names
8. supported operators: + - / * % ^ (plus, minus, divide, multiple, modulo, exponent)
9. PRINT – syntax PRINT expression. If the expression is a variable, and this variable is not in scope,
then an error message indicating unknown variable x at line number y. The value printed if there is a
variable in scope should be the variable with the closest scope.
10. Errors – other than the print statements, our interpreter will not be responsible for detecting errors,
syntax errors should be disregarded if encountered, assume that the source file is correct.
Our hash function: sum the ordinal values of the characters of the variable multiplied by their position in
the string (1-indexing), then taking the modulo by TABLESIZE.
1. The variable ABC = (65 * 1 + 66 * 2 + 67 * 3) % TABLESIZE
All tokens are separated by one space or a new line.
?
Program 4
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Output: for this assignment, run your interpreter on this sample source program as well as a program of
your own, and turn it the output from both, as well as the source code from your BORG program as well
as source code of the assignment and its executable.
Example Submission:
BorgInterpretor.cpp
HelloWorld.txt
output.txt (or as a comment in the cpp file)
X-Credit. Each student may implement one additional feature to the language, such as adding if, switch,
for, while, methods, more capable print statements. Only one student may implement a given extension
to the language, and each extension must first be cleared with me.
Sample program and its output:
Input Output
COM HERE IS OUR FIRST BORG PROGRAM
COM WHAT A ROBUST LANGUAGE IT IS
START
VAR BORAMIR = 25
VAR LEGOLAS = 101
PRINT BORAMIR BORAMIR IS 25
BORAMIR ++
PRINT LEGOLAS LEGOLAS IS 101
PRINT GANDALF GANDALF IS UNDEFINED
PRINT BORAMIR * 2 BOARAMIR * 2 IS 52
COM
Program 4
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COM NESTED BLOCK
COM
START
VAR GANDALF = 49
PRINT GANDALF GANDALF IS 49
PRINT BORAMIR BORAMIR IS 26
FINISH
PRINT GANDALF GANDALF IS UNDEFINED
START
LEGOLAS = 1000
PRINT LEGOLAS LEGOLAS IS 1000
FINISH
PRINT LEGOLAS LEGOLAS IS 1000
LEGOLAS --
PRINT LEGOLAS LEGOLAS IS 999
FINISH
Program 4
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