[unix-history] / .ref-5cb41021d721f4e0ac572d592613f963e495d1ff / .ref-BSD-3 / usr / lib / learn / C / L31.1a

#print
Write a function named "rev(s)" which reverses
the string "s" in place. Name the file that contains
the function "rev.c".
When you're satisfied, type "ready".
#once #create Ref
cbax0987654321
#once #create tzaqc.c
main(){
	char *s1, *s2, *s3, *s4;
	s1 = "abc";
	s2 = "x";
	s3 = "";
	s4 = "1234567890";
	rev(s1);
	rev(s2);
	rev(s3);
	rev(s4);
	printf(s1);
	printf(s2);
	printf(s3);
	printf(s4);
	printf("\n");
}
#user
cc tzaqc.c rev.o
a.out >value
#cmp value Ref
#succeed
One way:

rev (s)
char *s;
{
	char *p;
	int t;
	
	for (p=s; *p; p++)
		;
	for (p--; p > s; p--, s++) {
		t = *p;
		*p = *s;
		*s = t;
	}
}
#log
#next
32.1a 10
Commit	Line	Data
fd15fd37 BJ	1	#print
	2	Write a function named "rev(s)" which reverses
	3	the string "s" in place. Name the file that contains
	4	the function "rev.c".
	5	When you're satisfied, type "ready".
	6	#once #create Ref
	7	cbax0987654321
	8	#once #create tzaqc.c
	9	main(){
	10	char s1, s2, s3, s4;
	11	s1 = "abc";
	12	s2 = "x";
	13	s3 = "";
	14	s4 = "1234567890";
	15	rev(s1);
	16	rev(s2);
	17	rev(s3);
	18	rev(s4);
	19	printf(s1);
	20	printf(s2);
	21	printf(s3);
	22	printf(s4);
	23	printf("\n");
	24	}
	25	#user
	26	cc tzaqc.c rev.o
	27	a.out >value
	28	#cmp value Ref
	29	#succeed
	30	One way:
	31
	32	rev (s)
	33	char *s;
	34	{
	35	char *p;
	36	int t;
	37
	38	for (p=s; *p; p++)
	39	;
	40	for (p--; p > s; p--, s++) {
	41	t = *p;
	42	p = s;
	43	*s = t;
	44	}
	45	}
	46	#log
	47	#next
	48	32.1a 10