In your Lab assignment, you should have parsed the input expression from the keyboard, echoed it to the screen and called a subroutine with the input. In this MP you will write code to use a stack to
evaluate the expression. If the read value is an operand, push it onto the stack. If the read value is an operator, pop two values from the stack, apply the operator on the two values and push the result
back on the stack. Keep repeating this for every value read from keyboard and stop when you reach the ASCII value of the "=" (equal sign) character. If the last value is an operand, that means
the expression was invalid. If there is a stack underflow during any point in this process, then the expression was invalid. Do not worry about stack overflows. Look at the flowchart below for a detailed
description of the algorithm.
MP2 is due on Thursday, Sept. 21, by 10pm in your svn repository.
MP2_testcases. docx
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For example if the input the user entered on the keyboard was "3 4 -=", then the stack through the evaluation of the expression will be-
Start Read "3"(push x0003) Read "4"(push x0004) Read "-"(pop, calculate and push)
x0000 x0000 x0000 x0000
x0000 x0000 x0004 x0000
x0000 x0003 x0003 x
Examples:
Input Solution in decimal (stored in R5 as binary) Hexadecimal Output on screen
4 5 + 3 * 7 -= 20 (0000000000010100) x0014
5 2 8 * + 3 -= 18 (0000000000010010) x0012
5 1 2 + 4 * + 3 -= 14 (0000000000001110) x000E