Function & its Declaration

     The typical way of something done in C++ programs is to 
call a function.Defining a function is the way you specify how 
an operation is to be done.Whenever a function is defined must 
specify a return type to indicate the type of the value returned by
 the function when it complete its task.A function cannot be called
 unless it has been declared.
    Function declaration gives the name of the function,the type 
of value returned (if any) by the function and the number of function,
types of  arguments must be supplied in a 'call' of the function.
Each function in a program performs a task and may return a value.