Input and Output Using Characters

The input term and output term are straightforward. Sometimes it is complex to use the full stops and quotes, and it is not always suitable. For example, to define a predicate that would read characters in series from the keyboard and count the number of vowels is really tedious. For this kind of problem, a better approach is to input a character at a time. To apply this approach, we have to know the ASCII value of the characters. ASCII (American Standard Code for Information Interchange) value is an integer from 0 to 255.

All non-printing characters and printing characters have their corresponding ASCII value. ASCII value of characters, which is less than or equal to 32 is called as control characters or white space characters.

The following table shows the ASCII values of printable characters and some others.

Number	Character	Description
9	Tab
10	end of record
32		space
33	!	exclamation mark
34	“	quotation mark
35	#	number sign
36	$	dollar sign
37	%	percent sign
38	&	ampersand
39	‘	apostrophe
40	(	left parenthesis
41	)	right parenthesis
42	*	asterisk
43	+	plus sign
44	,	comma
45	-	hyphen
46	.	period
47	/	slash
48	0	0 digit
49	1	1 digit
50	2	2 digit
51	3	3 digit
52	4	4 digit
53	5	5 digit
54	6	6 digit
55	7	7 digit
56	8	8 digit
57	9	9 digit
58	:	colon
59	;	semicolon
60	<	less-than
61	=	equals-to
62	>	greater-than
63	?	question mark
64	@	at sign
65	A	uppercase A
66	B	uppercase B
67	C	uppercase C
68	D	uppercase D
69	E	uppercase E
70	F	uppercase F
71	G	uppercase G
72	H	uppercase H
73	I	uppercase I
74	J	uppercase J
75	K	uppercase K
76	L	uppercase L
77	M	uppercase M
78	N	uppercase N
79	O	uppercase O
80	P	uppercase P
91	Q	uppercase Q
82	R	uppercase R
83	S	uppercase S
84	T	uppercase T
85	U	uppercase U
86	V	uppercase V
87	W	uppercase W
88	X	uppercase X
89	Y	uppercase Y
90	Z	uppercase Z
91	[	left square bracket
92	\	backslash
93	]	right square bracket
94	^	Caret
95	_	underscore
96	`	grave accent
97	A	lowercase a
98	B	lowercase b
99	C	lowercase c
100	D	lowercase d
101	E	lowercase e
102	F	lowercase f
103	G	lowercase g
104	H	lowercase h
105	I	lowercase i
106	J	lowercase j
107	K	lowercase k
108	L	lowercase l
109	M	lowercase m
110	N	lowercase n
111	O	lowercase o
112	P	lowercase p
113	Q	lowercase q
114	R	lowercase r
115	S	lowercase s
116	T	lowercase t
117	U	lowercase u
118	V	lowercase v
119	W	lowercase w
120	X	lowercase x
121	Y	lowercase y
122	Z	lowercase z
123	{	left curly brace
124	\|	vertical bar
125	}	right curly brace
126	~	tilde