A keyword has a special meaning in the C language. You must spell keywords as shown in the following list, and you cannot use them as user-defined names (see above).
__asmauto__based breakcase__cdecl char const continue default do double else__emit enum__export extern__far__fastcall float for__fortran goto__huge if int__interrupt__loadds long__near__pascal register return__saveregs__segment__segname__self short signed sizeof static struct switch typedef union unsigned void volatile while
A few other words, such as main, have a special meaning but are not keywords in the strict sense. Use online help to get details on all such words.