l30.1a

<B>Digital的Unix操作系统VAX 4.2源码</B>

#print
Write a subroutine named "locn(s,c)" which expects two
arguments: the first is a pointer to characters 's' which
points to a null-terminated string, and the second
is a character 'c' which is to be searched for in the
string 's'.  If the character 'c' does not
appear in the string return 0; otherwise return a pointer
to the position of 'c' in the string. Name the program "locn.c";
as usual, compile and test it and then type "ready".
#once #create Ref
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#once #create tzaqc.c
char *alpha "abcdefghijklmnopqrstuvwxyz";
main()
{
	extern char *locn();
	printf("%d\n", locn(alpha, '+'));
	printf("%d\n",locn(alpha, 't')-alpha);
	printf("%d\n",locn(alpha, 'a')-alpha);
	printf("%d\n",locn(alpha, 'z')-alpha);
	printf("%d\n",locn("", 'z'));
}
#user
cc tzaqc.c locn.o
a.out  >value
#cmp value Ref
#succeed
/* Try this: */

char *
locn (s, c)
char *s;
{
	for( ; *s; s++)
		if (*s == c)
			return(s);
	return(0);
}
#log
#next
31.1a 10