IMPORTANT There is sample code for this assignment. Please study that and use it as a template

before you start coding.

Description. An accumulator is a primitive kind of calculator that can evaluate arithmetic expressions. In fact, the Arithmetic$-$Logic Unit $($ALU$)$ of the first computers was just an accumulator. An

arithmetic expression, as you know, consists of two kinds of tokens: operands and operators.

All our operands will be $($float$)$ numbers and for a start, we shall use only two operators: $+($plus$)$

and $-($minus$).$ A sample run of the program would look like this.

Welcome to your friendly neighborhood accumulator! Please input

your expression, starting with an operand and

type in $=$ when completed.

$3\mathrm{.}0$

$+$

$2\mathrm{.}0$

$-$

$-5\mathrm{.}2$

$=$

The answer is $10\mathrm{.}2$

Thank$-$you for using your friendly neighborhood accumulator!

Note that the equals sign acts like a sentinel to mark the end of the input. The problem is

formally described as follows:

Input: An alternating sequence of operands and operators, starting and ending with an operand.

The sequence is followed by an equals sign, to indicate termination. Each operand is a float value

and each operator is a plus or a minus.

Output: The value of the expression defined by the sequence of operands and operators.

Assumption. We shall assume for now that the user will not make mistakes when using the

accumulator, i$.$e$.,$ there is no bad input $($e$.$g$.,$ two consecutive tokens being both operands or

both operators, other unexpected characters etc.$)$

The Strategy. To initialize the process, the first operand $($a number$)$ is read and stored as the

total. Next, an operator $($a character$)$ is read and we decide what action to take. The action can

be one of the following:

$($i$)$ In case of termination $($equals sign$)$ the process is exited and the total is printed;

$($ii$)$ otherwise another operand is read and either added to or subtracted from the total depending

on the operator.

Question $1$: Create a suitable set of tests and list them in a testing table. Think of what tests

$1$

would be of particular interest, and put in comments in the testing table explaining why you chose

them.