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Here is an example of decoding argument types for a format string. We
assume this is part of an interpreter which contains arguments of type
NUMBER
, CHAR
, STRING
and STRUCTURE
(and
perhaps others which are not valid here).
/* Test whether the nargs specified objects in the vector args are valid for the format string format: if so, return 1. If not, return 0 after printing an error message. */ int validate_args (char *format, int nargs, OBJECT *args) { int *argtypes; int nwanted; /* Get the information about the arguments. Each conversion specification must be at least two characters long, so there cannot be more specifications than half the length of the string. */ argtypes = (int *) alloca (strlen (format) / 2 * sizeof (int)); nwanted = parse_printf_format (string, nelts, argtypes); /* Check the number of arguments. */ if (nwanted > nargs) { error ("too few arguments (at least %d required)", nwanted); return 0; } /* Check the C type wanted for each argument and see if the object given is suitable. */ for (i = 0; i < nwanted; i++) { int wanted; if (argtypes[i] & PA_FLAG_PTR) wanted = STRUCTURE; else switch (argtypes[i] & ~PA_FLAG_MASK) { case PA_INT: case PA_FLOAT: case PA_DOUBLE: wanted = NUMBER; break; case PA_CHAR: wanted = CHAR; break; case PA_STRING: wanted = STRING; break; case PA_POINTER: wanted = STRUCTURE; break; } if (TYPE (args[i]) != wanted) { error ("type mismatch for arg number %d", i); return 0; } } return 1; }