What is wrong with this code ?

[The Lint Program]

In article <1156 at nsscb.UUCP> nrg at nsscb.UUCP (G.Narotham Reddy) writes:
	main(argc,argv)
	int argc;
	char *argv[];
	{
	struct stat nfile;
	stat(argv[1], &nfile);
	if (nfile.st_mode & S_IFMT == S_IFREG) 
	printf("%s regular file\n", argv[1]);    
	else if (nfile.st_mode & S_IFMT == S_IEXEC) 
	printf("%s executable\n", argv[1]);    
	else if (nfile.st_mode & S_IFMT == S_IWRITE) 
	printf("%s writable\n", argv[1]);    
	else if (nfile.st_mode & S_IFMT == S_IREAD) 
	printf("%s readable\n", argv[1]);    
	else if (nfile.st_mode & S_IFMT == S_IFDIR)
	printf("%s dir\n", argv[1]);    
	}

t.c(11): warning: constant in conditional context
t.c(11): warning: null effect
t.c(13): warning: constant in conditional context
t.c(13): warning: null effect
t.c(15): warning: constant in conditional context
t.c(15): warning: null effect
t.c(17): warning: constant in conditional context
t.c(17): warning: null effect
t.c(19): warning: constant in conditional context
t.c(19): warning: null effect
t.c(6): warning: argument argc unused in function main
stat returns value which is always ignored
printf returns value which is always ignored