In the postfix expression evaluation example, the two most re- cent operands are popped when an operator is encountered so that the sub-expression can be evaluated. The first operand popped is treated as the second operand in the sub-expression, and the second operand popped is the first. Give and explain an example that demonstrates the importance of this aspect of the solution.
What will be an ideal response?
For operations such as addition and multiplication, the order of operands does not matter, but for subtraction and division, for instance they do. So the postfix expression
17 4 -
means to subtract 4 from 17 (and not the other way around). When these operands are pushed onto the stack, 17 goes on first, then 4 on top. So when they are popped to be evaluated, the first value popped must be treated as the second operand.
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