Write a lexical analyzer program to scan a postfix mathematical expressions $($input file$)$ and recognize the lexemes as their respective tokens. The program should identify the lexemes, identify their corresponding tokens and produce a table of lexemes and tokens as output. Required:

$1.$ A complete program listing

$2.$ A description of your program $-$ what it does, how it operates, data structures used, input requirements $($is the input interactive via the user or is it from a file$),$ what does the output represent, etc.

$3.$ Test runs $($run your program and print the screen results$)$

$4.$ Also in your description, you should explain why you chose the test run data $($input$)$ that you chose. That is$,$ what did you test for? For example: I am testing the program to read a long string, or I am

testing the program to handle incorrect input, etc Do it in c$++.$