Make a program in C++ that converts infix arithmetic expression to a postfix expression using Shunting Yard algorithm and Stacks. This program must read an infix expression from user input, and generate the postfix expression as output. It assumes that the expressions are all correct. Please include all code in C++ programming language.

It must pass the following test cases:

CASE 1: INFIX: (A + B) * C

PASSED IF RESULT IS AB+C*

CASE 2: INFIX: A + B * C + D

PASSED IF RESULT IS ABC*+D+

CASE 3: INFIX: (A + B) * (C + D)

PASSED IF RESULT IS AB+CD+*

CASE 4: INFIX: A * B + C * D

PASSED IF RESULT IS AB*CD*+

CASE 5: INFIX: A + B + C + D

PASSED IF RESULT IS AB+C+D+

CASE 6: INFIX: 67 + ( 32 / 8 ) * 3 rt 8

PASSED IF RESULT IS: 67 32 8 / 3 8 rt * +