Character Set in C || Gate Notes

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In C programming, a charactеr refers to thе collеction of charactеrs that can bе usеd to writе C programs. C usеs a charactеr sеt known as thе ASCII (American Standard Codе for Information Intеrchangе) charactеr sеt, which is a widеly-usеd charactеr еncoding standard.

The C programming language was created to provide effective computing utility for programmers.
It supports 265 valid characters. It comprises various kinds of characters such as alphabets, digits, white spaces, etc.
It provides a simple way for programmers to express operations using a standardised set of symbols.

Table of Content

Character set in C in Programming language
Uses of Character Set in C
Types of characters
ASCII values
Summary of all types of characters in C
Things to Remember
Sample Questions

Key Terms- Characters, ASCII, Programming, Digits, Values, Alphabets, Symbols

Character Set C in a Programming Language

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In computer programming, code points or numericals are assigned to represent specific characters. A set of values which represent different characters is called a character set.

Different programming languages have different valid codings and thus support different sets of characters.
C can be combined to form words, phrases and sentences.
Understanding the character set is crucial for computer science students as it forms the building blocks of each C program.

Uses of Character Set in C

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The uses of Character Set in C are mentioned below:

The character set supports a wide range of commonly used alphabets to represent the source programme.
Many symbols such as '+', ()* & ^ are usually required in computers.
So the programming language provides ASCII values for a set of commonly used symbols as well.
By using the character set we can form words by combining different alphabets and in turn we may create phrases & sentences as well.

Read More: Introduction To Array

ASCII Values

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The American Standard Code for Information Interchange (ASCII) values are numerical codes which are programmed to represent a specific character in the C programming language.

For example, the ASCII value 97 denotes a lowercase 'a'.
Similarly, each character has a corresponding ASCII Value which can be coded up to 8 bits.
ASCII uses seven-digit binary numbers- i.e., numbers consisting of various sequences of 0's and 1's.

Since there are 128 different possible combinations of seven 0's and 1's, the code can represent 128 different characters.

Control characters- In computer programming there are certain characters which are used to initiate or execute an action rather than printing graphic characters on the screen.
In ASCII standard, there are 33 control characters such as escape, new line non-breaking space, tab character, etc.
Printable characters- Characters which represent and display text forms of characters on the screen are called printable characters.
Printable characters include alphabets, digits, punctuation marks such as full stop, brackets, commas, question marks, etc. They range from 32 to 126 in ASCII Values.

Given is a chart of printable characters in hex and decimal format.

HEX	DEC	CHARACTER	HEX	DEC	CHARACTER	HEX	DEC	CHARACTER
0x20	32	<SPACE>	0x40	64	@	0x60	96	`
0x21	33	!	0x41	65	A	0x61	97	a
0x22	34	“	0x42	66	B	0x62	98	b
0x23	35	#	0x43	67	C	0x63	99	c
0x24	36	$	0x44	68	D	0x64	100	d
0x25	37	%	0x45	69	E	0x65	101	e
0x26	38	&	0x46	70	F	0x66	102	f
0x27	39	‘	0x47	71	G	0x67	103	g
0x28	40	(	0x48	72	H	0x68	104	h
0x29	41	)	0x49	73	I	0x69	105	i
0x2A	42	*	0x4A	74	J	0x6A	106	j
0x2B	43	+	0x4B	75	K	0x6B	107	k
0x2C	44	,	0x4C	76	L	0x6C	108	l
0x2D	45	–	0x4D	77	M	0x6D	109	m
0x2E	46	.	0x4E	78	N	0x6E	110	n
0x2F	47	/	0x4F	79	O	0x6F	111	o
0x30	48	0	0x50	80	P	0x70	112	p
0x31	49	1	0x51	81	Q	0x71	113	q
0x32	50	2	0x52	82	R	0x72	114	r
0x33	51	3	0x53	83	S	0x73	115	s
0x34	52	4	0x54	84	T	0x74	116	t
0x35	53	5	0x55	85	U	0x75	117	u
0x36	54	6	0x56	86	V	0x76	118	v
0x37	55	7	0x57	87	W	0x77	119	w
0x38	56	8	0x58	88	X	0x78	120	x
0x39	57	9	0x59	89	Y	0x79	121	y
0x3A	58	:	0x5A	90	Z	0x7A	122	z
0x3B	59	;	0x5B	91	[	0x7B	123	{
0x3C	60	<	0x5C	92	\	0x7C	124	\|
0x3D	61	=	0x5D	93	]	0x7D	125	}
0x3E	62	>	0x5E	94	^	0x7E	126	~
0x3F	63	?	0x5F	95	_	-	-	-

Types of characters in Character Set in C

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The characters in the C programming language can be distinctly divided into two categories-

Source character set- Source character set is the compilation of those characters in the C language which may be used in the C source code before the preprocessing phase.
Execution character set- The set of characters which can store character string constants and can be interpreted by the running program is called the execution character set. It includes control characters, escape sequences and characters of the basic subset.
Basic character set- This character set includes common characters of both the source character set and an execution character set.
Alphabets- The C language supports all 26 alphabets in both lowercase and uppercase forms.

Uppercase alphabets	ASCII Value
A	65
B	66
C	67
D	68
E	69
F	70
G	71
H	72
I	73
J	74
K	75
L	76
M	77
N	78
O	79
P	80
Q	81
R	82
S	83
T	84
U	85
V	86
W	87
X	88
Y	89
Z	90

Lowercase Alphabets	ASCII Value
a	97
b	98
c	99
d	100
e	101
f	102
g	103
h	104
i	105
j	106
k	107
l	108
m	109
n	110
o	111
p	112
q	113
r	114
s	115
t	116
u	117
v	118
w	119
x	120
y	121
z	122

Digits- The 10 constituent digits of numerical values are included in the C programming language

DIGITS	ASCII value
0	48
1	49
2	50
3	51
4	52
5	53
6	54
7	55
8	56
9	57

Special Symbols- Symbols like brackets (,[,),] and ×,÷,=,*,& are often used to facilitate communication. There is a set of commonly used symbols in the C programming language as well.

Special Symbols	ASCII Value
~	126
!	33
@	64
#	35
$	36
%	37
&	38
*	42
(	40
)	41
‘	39
“	34
<	60
\	92
;	58
:	59
/	47
?	63
>	62
–	45
_	95
+	43
=	61
{	123
}	125
\|	124

White Space- whitespace is any character or series of characters that represent horizontal or vertical space in typography in computer programming.

White Space	Meaning
\0	null
\b	blank space
\t	horizontal tab
\v	vertical tab
\’	single quote
\”	double quote
\?	Question mark
\a	alarm (bell)
\r	carriage return
\f	form feed
\n	new line
\\	back slash

Summary of all the Characters in C

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Here is the summary in the tabulated form:

CONTROL CHARACTERS	ASCII Value	Character
0	NULL	Null
1	SOH	Start of Header
2	STX	Start of Text
3	ETX	End of Text
4	EOT	End of Transaction
5	ENQ	Enquiry
6	ACK	Acknowledgement
7	BEL	Bell
8	BS	Backspace
9	HT	Horizontal Tab
10	LF	Line Feed
11	VT	Vertical Tab
12	FF	Form Feed
13	CR	Carriage Return
14	SO	Shift Out
15	SI	Shift In
16	DLE	Data Link Escape
17	DC1	Device Control 1
18	DC2	Device Control 2
19	DC3	Device Control 3
20	DC4	Device Control 4
21	NAK	Negative Acknowledgement
22	SYN	Synchronous Idle
23	ETB	End of Trans Block
24	CAN	Cancel
25	EM	End of Medium
26	SUB	Substitute
27	ESC	Escape
28	FS	File Separator
29	GS	Group Separator
30	RS	Record Separator
31	US	Unit Separator
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	DEL	-

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Things to Remember

C programming language is a general purpose programming language used to create software, databases and operating systems like windows etc.
It has a total of 256 characters.
It has different kinds of characters like printable, escape sequences, control characters etc.
Control characters are used to carry out any action, while printable characters are utilized to print characters on display.
Printable characters include digits, special symbols, White spaces and all english alphabets in lowercase and uppercase.
Any character outside the character set is not supported by the program and shows invalid when entered.

Sample Questions

Ques. C programming language was developed by (1 mark)
a) Dennis Ritchie
b) Ken Thompson
c) Bill Gates
d) Peter Norton

Ans: (a)

Explanation: The American Computer scientist Dennis Ritchie designed the C programming language which gained great significance in the latter years.

Ques. C was developed in the year ___ (1 mark)
a) 1970
b) 1972
c) 1976
d) 1980

Ans: (b)

Dennis Ritchie developed the C programming language at Bell Labs of AT&T (American Telephone and Telegraph) located in the U.S. in 1972.

Ques. Which of the following are tokens in C? (1 mark)
a) Keywords
b) Variables
c) Constants
d) All of the above

Ans: (d)

Explanation: Tokens are the smallest building units of a C program. Each and every word, mark or punctuation you come across in a C program is a token. Therefore Keywords variables, constants, and identifiers are all tokens.

Ques. The maximum length of a variable in C is ___ (1 mark)
a) 8
b) 16
c) 32
d) 64

Ans: (a)

Explanation: The maximum integral value which you can fit in a variable is 8 bytes. Therefore the Ans will be

Ques. Which of the following options is correct if one wants to exchange the values of x and y variables? (1 mark)
(a) We need to call Swap(x,y)
(b) we need to call swap(&x,&y)
(c) We can not call swap (x,y) because it does not return any value
(d) We can not call swap (x,y) because parameters are passed by value

Ans : (d)

Explanation: Option a, b and c are incorrect because of the following reason.

(a) We need to call Swap(x,y)

(b) we need to call call swap(&x,&y)

In order to exchange the value of x and y we should call swap(&x, & y) but for it’s working at the time of function definition we should pass parameter as a pointer it means we should define void swap( int *x, int*y)

So function call Swap(x,y) can not not be used because the parameter is passed as a value instead of pointer types arguments.

Ques. What does the following C statement declare? [GATE 2005] (1 mark)
int (*f)(int *);
(a) A function that takes an integer pointer as an argument and returns an integer.
(b) A function that takes an integer as an argument and returns an integer pointer.
(c) A pointer to a function that takes an integer pointer as an argument and returns an integer.
(d) A function that takes an integer pointer as an argument and returns a function pointer.

Ans: Option C is correct Ans because int(*f)(int *); is a statement which represents a pointer to a function that takes an integer argument and returns an integer.

Ques. What does the following fragment of C-program print? [GATE 2011] (1 mark)
char c[ ] = “GATE2011”;
char *p = c;
printf(“%s”, p + p[3] – p[1]);
(a) GATE 2011
(b) E2011
(c) 2011
(d) 01

Ans: C

Solution: char c[ ] = “GATE2011”;

since char *p =c it means p represents to the base address of string “2011”

SO p[3] is ‘E’ and p[1] is ‘A’.

Value of Sub expression p[3] – p[1] = ASCII value of ‘E’ – ASCII value of ‘A’ = 4

// So the expression p + p[3] – p[1] becomes ( p + 4) which is

And (p+4) represent to base address of string “2011”

printf(“%s”, p + p[3] – p[1]);

So it will print 2011

Ques. The output of the following C program is_____ [ GATE 2015]. (3 marks)
void f1(int a, int b)
{
int c;
c=a; a=b; b=c;
}
void f2(int *a, int *b)
{
int c;
c=*a; *a=*b; *b=c;
}
int main(){
int a=4, b=5, c=6;
f1(a,b);
f2(&b, &c);
printf(“%d”,c-a-b);
}

Ans. -5

Explanation: The first function call f1(a,b) has no effect because here the parameters are passed as call by value. So function signatures don’t match.

Second function call f2(&b,&c) signature matched. So it will work correctly . So value of variable b and c will be swapped and new value of b will be 6 and c will be 5 so c-a-b will be = 5-6-4= -5

Ques. Consider the following C program [ GATE 2018] (3 marks)
#include< stdio.h >
void fun1(char *s1, char *s2){
char *tmp;
tmp = s1;
s1 = s2;
s2 = tmp;
}
void fun2(char **s1, char **s2){
char *tmp;
tmp = *s1;
*s1 = *s2;
*s2 = tmp;
}
int main(){
char *str1 = “Hi”, *str2 = “Bye”;
fun1(str1, str2); printf(“%s %s “, str1, str2);
fun2(&str1, &str2); printf(“%s %s”, str1, str2);
return 0;
}
The output of the program above is

Ans. fun1(char *s1, char *s2)

This function has a local scope therefore the value changed here won’t affect actual parameters and values will be ‘Hi Bye’.

Let’s understand second function

fun2(char **s1, char **s2)

Since here in this function value is pointer to pointer, it will change the pointer of the actual value. In this case values will be ‘Bye Hi’

So the Ans is ‘Hi Bye Bye Hi’

Ques. Consider the following C program: GATE [2019] (3 marks)
#include < stdio.h >
int main()
{
int a[] = {2, 4, 6, 8, 10} ;
int i, sum = 0, *b = a + 4 ;
for (i = 0; i < 5; i++)
sum = sum + (*b – i) – *(b – i) ;
printf (“%d\n”, sum) ;
return 0 ;
}
The output of the above C program is _____.

Ans. 10

Explanation: In the above program the loop will be run from i=0 to i=4.

When i=0 then

Sum= 0+10-0 =0

When i= 1 then

Sum = 0+9-8

Sum=1

When i=2 then

Sum=1+8-6=3

When i=3 then

Sum=3+7-4=6

When i =4 then

Sum= 6+ 6-2=10

So output will be 10.

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Character Set in C: Uses, Types & ASCII Values

Character Set C in a Programming Language

Uses of Character Set in C

ASCII Values

Types of characters in Character Set in C

Summary of all the Characters in C

Things to Remember

Sample Questions

Comments

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Uppercase alphabets	ASCII Value
A	65
B	66
C	67
D	68
E	69
F	70
G	71
H	72
I	73
J	74
K	75
L	76
M	77
N	78
O	79
P	80
Q	81
R	82
S	83
T	84
U	85
V	86
W	87
X	88
Y	89
Z	90

Lowercase Alphabets	ASCII Value
a	97
b	98
c	99
d	100
e	101
f	102
g	103
h	104
i	105
j	106
k	107
l	108
m	109
n	110
o	111
p	112
q	113
r	114
s	115
t	116
u	117
v	118
w	119
x	120
y	121
z	122

Special Symbols	ASCII Value
~	126
!	33
@	64
#	35
$	36
%	37
&	38
*	42
(	40
)	41
‘	39
“	34
<	60
\	92
;	58
:	59
/	47
?	63
>	62
–	45
_	95
+	43
=	61
{	123
}	125
\|	124

Uppercase alphabets	ASCII Value
A	65
B	66
C	67
D	68
E	69
F	70
G	71
H	72
I	73
J	74
K	75
L	76
M	77
N	78
O	79
P	80
Q	81
R	82
S	83
T	84
U	85
V	86
W	87
X	88
Y	89
Z	90

Lowercase Alphabets	ASCII Value
a	97
b	98
c	99
d	100
e	101
f	102
g	103
h	104
i	105
j	106
k	107
l	108
m	109
n	110
o	111
p	112
q	113
r	114
s	115
t	116
u	117
v	118
w	119
x	120
y	121
z	122

Special Symbols	ASCII Value
~	126
!	33
@	64
#	35
$	36
%	37
&	38
*	42
(	40
)	41
‘	39
“	34
<	60
\	92
;	58
:	59
/	47
?	63
>	62
–	45
_	95
+	43
=	61
{	123
}	125
\|	124

Uppercase alphabets	ASCII Value
A	65
B	66
C	67
D	68
E	69
F	70
G	71
H	72
I	73
J	74
K	75
L	76
M	77
N	78
O	79
P	80
Q	81
R	82
S	83
T	84
U	85
V	86
W	87
X	88
Y	89
Z	90

Lowercase Alphabets	ASCII Value
a	97
b	98
c	99
d	100
e	101
f	102
g	103
h	104
i	105
j	106
k	107
l	108
m	109
n	110
o	111
p	112
q	113
r	114
s	115
t	116
u	117
v	118
w	119
x	120
y	121
z	122

Special Symbols	ASCII Value
~	126
!	33
@	64
#	35
$	36
%	37
&	38
*	42
(	40
)	41
‘	39
“	34
<	60
\	92
;	58
:	59
/	47
?	63
>	62
–	45
_	95
+	43
=	61
{	123
}	125
\|	124