FUNCTION PROTOTYPING:ANSI C adopts c++ function prototype technique where function definaton and declaration include function names,arguments t,data types and return value data types.function prototype enable ANSI ccompilers to check for function call in user program that passes invalid number number of argument or incompatiblle argument data types.these fix a major weakness of the K&R C compilers:invalid call in user program often passes compilation but cause program to crash when they are executed