write a program in c++

Read an infix expression from an input file and convert to postfix. Instead of displaying directly on the screen, first place in a queue, and then display the contents of the queue on the screen.

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:

1+2

converts to

12+