_toupper(3)                                                 _toupper(3)

  toupper()

  NAME

    toupper(), _toupper() - lower case to upper case letter conversion

  SYNOPSIS

    #include 

    int toupper (int c)
    int _toupper (int c)

  DESCRIPTION

    The toupper(3) function converts a lower-case letter to the corresponding
    upper-case letter. If c is not a lower-case letter, it is not converted.

    The _toupper(3) function does the same, but the argument c must be a
    lower-case letter. This routine is faster but will break with the wrong
    input.

  RETURN VALUES

    If the argument is a lower-case letter, the toupper(3) function returns
    the corresponding upper-case letter if there is one; otherwise the
    argument is returned unchanged.

  SEE ALSO

    isascii(3)

    isalnum(3)

    isalpha(3)

    isblank(3)

    iscntrl(3)

    isdigit(3)

    isgraph(3)

    islower(3)

    isprint(3)

    ispunct(3)

    isspace(3)

    isupper(3)

    isxdigit(3)

    tolower(3)

  USAGE NOTES

    All these functions are thread safe.

    None of these functions are async-signal safe.