Thread: student needs help with C strings

alright, i need help on a project in class. Im new with C so be gentle
i have a series of statically assigned character arrays that i need to append and prepend. So heres the scenario:

str1 [17]

str1 takes user input in the form of three characters at a time in a loop, i need to:
a) append the three characters to the end of the string, when the length goes beyond 17 it needs to start dropping characters off the begining.
b) prepend the three characters to the beginning of the string, when the length goes beyong 17 characters it needs to start dropping characters off the the end of the string.

ive been using the strcat() function for the appending, but cant figure out how to make it drop chars off the beginning. Also, is there a similar function for prepending?

all of this is being written on an XP box with SP2, and then being cross compiled to run on a motorola 68hc11 microcontroller.