embeded system c

1  Explain What are different qualifiers in C? 

1) Volatile: A variable should be declared volatile whenever its value could change unexpectedly. In practice, only three types of variables could change: ► Memory-mapped peripheral registers ► Global variables modified by an interrupt service routine ► Global variables within a multi-threaded application 2) Constant: The addition of a 'const' qualifier indicates that the (relevant part of the) program may not modify the variable.