3.22 Write a program to evaluate a postﬁx expression.
3.23 a. Write a program to convert an inﬁx expression that includes (, ), +, -, *, and /
b. Add the exponentiation operator to your repertoire.
c. Write a program to convert a postﬁx expression to inﬁx.
3.24 Write routines to implement two stacks using only one array. Your stack routines should not declare an overﬂow unless every slot in the array is used.