proj3.cc File Reference

#include <iostream>
#include <stack>
#include <stdexcept>
#include <string>

Include dependency graph for proj3.cc:

Classes
class	IllegalExprException
	Exception class thrown by illegal infix expression. More...

Typedefs
using	ValueType = int
	This program only does integer arithmetic (and it's pretty limited integer arithmetic, with only one-digit operands). More...

Functions
ValueType	processExpression (const string &expr) throw (IllegalExprException)
	Determine the value of an infix expression. More...
bool	isValidResponse (char response)
	Is a character a valid response? More...
bool	isYesResponse (char response)
	Is a character a "yes" response? More...
int	precedence (char op)
	Determine the precedence of an operator. More...
void	provideHelpIfNecessary (void)
	Print a help message if the user wants one.
void	execute (stack< ValueType > &valstack, stack< char > &opStack) throw (IllegalExprException)
	Do the binary operation using the top element of an operand stack and the top two elements an operator stack. More...
ValueType	doOperation (ValueType operandL, char operation, ValueType operandR) throw (IllegalExprException)
	Do a binary operation. More...
int	main (void)
	The usual main function.

Typedef Documentation

using ValueType = int

This program only does integer arithmetic (and it's pretty limited integer arithmetic, with only one-digit operands).

If we ever decide to do (say) floating point arithmetic, simply change the definition of ValueType. Of course, this would require us to work somewhat harder when dealing with operands.

Function Documentation

ValueType doOperation	(	ValueType	operandL,
		char	operation,
		ValueType	operandR
	)
throw	(	IllegalExprException
	)

Do a binary operation.

Parameters

operandL	the left operatand
operation	the operation to be performed
operandR	the right operatand

Exceptions

IllegalExprException

if the operation cannot be executed

Returns

the result of the operation

void execute	(	stack< ValueType > &	valstack,
		stack< char > &	opStack
	)
throw	(	IllegalExprException
	)

Do the binary operation using the top element of an operand stack and the top two elements an operator stack.

Parameters

valstack	a stack of operands
opStack	a stack of operators

Exceptions

IllegalExprException

if the operation cannot be executed

Postcondition

the binary operation at the top of opStack is applied to the two operands at the top of valstack and this value is pushed to the top of valstack

bool isValidResponse

(

char

response

)

Is a character a valid response?

Parameters

response

the first char in the user's response

Precondition

response is a valid character

Returns

true iff response is one of the following:
'Y', 'y', 'N', 'n', 'T', 't', 'F', 'f', '1', '0'

bool isYesResponse

(

char

response

)

Is a character a "yes" response?

Precondition

response is a valid response (in the sense of isValidResponse)

Returns

true iff Response is one of the following:
'Y', 'y', 'T', 't', '1'

int precedence

(

char

op

)

Determine the precedence of an operator.

Parameters

op	the operator in question

Precondition

op is one of '+', '-', '*', '/'

Returns

• 3 for multiplicative operations
• 2 for additive operations
• 1 for illegal operation
• 0 for a left parenthesis

ValueType processExpression	(	const string &	expr	)
throw	(	IllegalExprException
	)

Determine the value of an infix expression.

Parameters

expr	a string, supposedly representing an infix expression

Returns

the value of expr

Exceptions

IllegalExprException

if expr is not a legal infix expression