In most versions of
C++, including
Turbo C++,each standard
library has a header file that contains
function prototypes for the functions used in those libraries and
data type and constant
definitions, needed by those functions. Microsoft seems to be phasing these out. Basic header files include iostream.h, conio.h and math.h.
When declred in a program they are usually at the top, before any functions are used, depending on your programing practices, and will look like this
#include < stdio.h >