Reserve Words in C

A list of all the reserved words in C has been given below. The set of reserved words above is used to build up the basic instructions of C; you can not use them in programs as a variable name or identifier.
Please note that this list is somewhat misleading. Many more words are out of bounds. This is because most of the facilities which C offers are in libraries that are included in programs. Once a library has been included in a program, its functions are defined and you cannot use their names yourself.
C requires all of these reserved words to be in lower case. (This does mean that, typed in upper case, the reserved words could be used as variable names, but this is not recommended.)
(A "d" by the word implies that it is used as part of a declaration.)

auto d                       if
    break                        int d
    case                         long d
    char d                       register d
    continue                     return
    default                      short d
    do                           sizeof
    double d                     static d
    else                         struct
    entry                        switch
    extern d                     typedef d
    float d                      union d
    for                          unsigned d
    goto                         while

    also in modern implementations:

    enum d
    void d
    const d
    signed d
    volatile d