Good afternoon~thanks for reading my post firstly.I'm so happy when I found this forum cause there are many teachers and students here.I'm one of them.

I am an electronic enthusiast. I’m so interesting in play the chip and write program.However, I am a newbie.So I came here and ask someone to help me out !

It’s my first time to use this chip--PIC18F25K80. There is the datasheet of PIC18F25K80 : http://www.kynix.com/uploadfiles/pdf65976/PIC18F25K80-I2fSO_910348.pdf. However,after I build a project, I so upset that I found the MPLAB can’t recognize this processor.The MCC19 3.0 I used is a very old compiler. Here has nothing about the library of 25K80 or linked file.Is there need a updated compiler--MCC18 ? Or are there any wrong with the chip?
Your help will be appreciated !

It's unclear whether C18 3.0 predates the 18F25K80, but given your description ("nothing about the library or linked file", which I interpret as it not having precompiled libraries or a linker script for that chip) it sounds like it does- which is plausible given the 66K80 family data sheet revision history starts in 2010 and the most recent C18 version dates to the beginning of 2014.

It might work if you can update to the latest C18 (3.47), but in the long term you're probably better off switching to XC8, which is actively supported and probably technically superior in various ways. They also have documentation guiding users through migration from C18 to XC8 (DS50002184), but if you don't have any existing code it'll be easier to just study the new documentation.

Hi,tari
After updated the latest C18,the problems are solved.
Thank you so much! Your are so kind !