revdonewrong.c


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#include <u.h>
#include <libc.h>

void
swap(char *a, char *b)
{
	char tmp;

	tmp = *a;
	*a = *b;
	*b = tmp;
}

void
rev(char *s, ulong len)
{
	char *e;

	e = s+len;
	while(s != e)
		swap(s++, --e);
}

void
usage(void)
{
	fprint(2, "usage: %s text\n", argv0);
	exits("usage");
}

void
main(int argc, char *argv[])
{
	ARGBEGIN{
	default: usage();
	}ARGEND;
	if(argc != 1)
		usage();
	rev(argv[0], strlen(argv[0]));
	print("%s\n", argv[0]);
	exits(nil);
}