can i use MCLR/vpp/RE3 pin of pic18f4550 pic microcontroller for multifunction..can i use this pin as I/O though i have used this pin for icsp connector at same time????
Yes. You can use it for IO. but when programmer is connected through ICSP the pin will work for vpp and when you remove the programmer after programming there will be your new code inside the mcu which tells to use MCLR/vpp/RE3 pin as MCLR pin or I/O pin.