In C++, write a program that reads a postfix expression from an input file. Then, the program should evaluate the postfix format and display the results.

Use these concepts for the program:

1) Struct Node 2) Enqueue and Dequeue 3) Push and Pop 4) DO NOT USE classes 5) Possibly Stack

Precondition:

• The expression will be read from a file (input.txt) that contains a single line. There will be no spaces between the operands and the operators.
• The following operators are allowed: + - * /
  • The normal rules of precedence will apply.
• No error checking is necessary.
• The numbers will all be greater than 0 and less than 10 (positive, single digit numbers)

Example:

12+

Result is 3