I currently have an Arduino Uno, as you all know the atmega328 chip has more then 5 ADC ports however the uno only provides the ability to use 5 A0-A4. i need input from 7 IR sensors "monday to sunday".
Can i use the digital ports to input an analogue inputs (i know you can do the reverse which is use analog as extra digital ports), or will i have to use a standalone ADC before giving the signal to the digital port?
You cannot use a digital port as an analog in.
The analog inputs are acutally a 6:1 multiplexer to an ADC.
As KE7GKP suggested an additional external multiplexer such as the 4051 would be a good option. With this setup you will have 8 analog ins connected to a single analog pin on the Arduino. But you will need 3 pins to select the input channel.