On just about every computer these days, characters are represented in ASCII code. This code is simply a mapping of numbers to letters, digits, or symbols. The char type in C can be thought of as holding an actual character, but really it is just a number (the ASCII code of the character). You can treat a char as a number or a character, as you wish. For example, the declarations char c = 'A'; and char c = 65; are exactly equivalent, since 65 is the ASCII code for a capital A. In general, the first form is preferable because people can't be expected to have ASCII codes memorized. But knowing how ASCII codes are arranged is often useful. For example, using the knowledge that the alphabet of capital letters has consecutive ASCII codes, we can convert the character 'A' defined above into a 'C' by adding 2 to it.

Table of ASCII codes 
 32	 
 33	!
 34	"
 35	#
 36	$
 37	%
 38	&
 39	'
 40	(
 41	)
 42	*
 43	+
 44	,
 45	-
 46	.
 47	/
 48	0
 49	1
 50	2
 51	3
 52	4
 53	5
 54	6
 55	7
 56	8
 57	9
 58	:
 59	;
 60	<
 61	=
 62	>
 63	?
 64	@
 65	A
 66	B
 67	C
 68	D
 69	E
 70	F
 71	G
 72	H
 73	I
 74	J
 75	K
 76	L
 77	M
 78	N
 79	O
 80	P
 81	Q
 82	R
 83	S
 84	T
 85	U
 86	V
 87	W
 88	X
 89	Y
 90	Z
 91	[
 92	\
 93	]
 94	^
 95	_
 96	`
 97	a
 98	b
 99	c
100	d
101	e
102	f
103	g
104	h
105	i
106	j
107	k
108	l
109	m
110	n
111	o
112	p
113	q
114	r
115	s
116	t
117	u
118	v
119	w
120	x
121	y
122	z
123	{
124	|
125	}
126	~
127