The document discusses fundamental data types in C including integer, floating point, character, and void types. It describes how variables must be declared before use and explains basic type modifiers like short, long, and unsigned. The summary also covers integer storage sizes and ranges, floating point precision and representation, and type conversions in C using casts and arithmetic promotion.

1. 1
Fundamental Data Types
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2. 2
Declaration
• All variables must be declared before
being used.
– Tells compiler to set aside an appropriate
amount of space in memory to hold a value.
– Enables the compiler to perform operations
using the declared variables.
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3. 3
Basic Data Types
• char character
• int integer
• float floating-point
• double double floating-point
• void valueless
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4. 4
Modifying the Basic Types
• Type modifier:
signed unsigned long short
• When a type modifier is used by itself, then int is
assumed.
Modifier Same As
signed signed int
unsigned unsigned int
long long int
short short int
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5. 5
Data Type char
Have Seen:Chars are treated as small integers &
conversely small ints are treated as chars.
char c = ‘a’;
printf (“%c”, c + 1) b
printf (“%d”, c + 2) 99
Each char variable stored in 1 Byte 8 Bits:
27
26
25
24
23
22
21
20
128 64 32 16 8 4 2 1
a
0000110 1http://improvec.blogspot.in

6. 6
• String of binary digits are called bit
strings.
• A bit string is interpreted as a binary
number. bnbn-1
……
b2b1b0
0 1 1 0 0 0 0 1 a
• This bit string has the value:
1×26
+ 1×25
+ 1×20
= 97http://improvec.blogspot.in

7. 7
3 types:
1) char 2) unsigned char 3) signed char
Each uses 1 Byte.
Signed char -128 to 127
Unsigned char 0 to 255
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8. 8
INTEGERS : Include the natural counting
numbers and their negatives.
INTEGRAL DATA TYPES:
int short long unsigned
Data Type int
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9. 9
• The magnitude of the number that an int
variable can hold depends on
___________?
2 Byte word ~ -32 K To +32K
-215
, …, -3, -2, -1, 0, 1, 2, 3, …, 215
-1
4 Byte word ~ -2 Billion To +2 Billion
-231
, …. -3, -2, -1, 0, 1, 2, 3, …, 231
-1
word size(bits) of the machine is machine dependent
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10. 10
• Integer overflow:
– Value too large for defined Storage Location.
– Typically program continues to run but
incorrect results.
– The programmer must strive at all times to
avoid integer overflow.
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11. 11
Types short, long, unsigned
• short - used where conserving storage is a
concern (usually 2 Bytes).
-32 Thousand To +32 Thousand
-215
, -215
+1, …, -3, -2, -1, 0, 1, 2, 3, …, 215
-1
• long - needed for larger integers (usually 4
bytes).
-2 Billion To +2 Billion
31 31 31
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12. 12
• Unsigned - no sign bit, same number
bytes as int.
The range, u, of values:
0 ≤ u ≤ 2wordsize
-1
2 Byte word ~ 0 To + 64 Thousand
0, 1, 2, 3, …, 216
-1
4 Byte word ~ 0 To + 4 Billion
0, 1, 2, 3, …, 232
-1http://improvec.blogspot.in

13. 13
Suffix:
u - 20u
l – 20l
ul - 20ul
(case not significant)
IF no suffix with constant - system will choose the
first of : int - long - unsigned long
That can hold the value.
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14. 14
float double long double
• Suffixes for constants
f or F float 3.7 F
l or L long double 3.7 L
• Any unsuffixed floating constant is of type
double (working type).
The Floating Types
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15. 15
• Notation: exponential or decimal
Must have Exponent or Dec pt or Both.
1.234567e5 123456.7
1.234567e-3 0.001234567
0e0 correct 0.0
.e0 wrong
May not contain any blanks or special characters.
• Typical Storage: Float < Double
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16. 16
Precision: The number of significant decimal
digits that floating value carries.
Range: Limits of largest & smallest possible
values that can be in a variable of that
type.
Float: 4 Bytes - about 6 decimal places of
accuracy- single precision.
Double: 8 Bytes - about 15 decimal places
of accuracy- double precision.http://improvec.blogspot.in

17. 17
Internal Representation
FLOAT:
01 8 9 31
SEEEEEEEE mmmmm…m
DOUBLE:
01 11 12 63
SEEEEEEEEEEE mmmmmmm…m
Implied mantissa of 1 is not stored.
Sign bit (1 for neg-otherwise pos).http://improvec.blogspot.in

18. 18
Float:
Precision: 6 significant digits.
Range: 10-38
to 10+38
0.d1d2d3d4d5d6× 10n
Double:
Precision: 15 significant digits (252
≈ 1015
)
Range: 10-308
to 10+308
0.123451234512345 × 103
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19. 19
Note:
1. Not all Real numbers are exactly
representable in binary memory.
2. Floating Arithmetic ops, unlike integer
arithmetic, may not be exact.
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20. 20
• Unary operator used to find the number of Bytes
needed to store an object.
sizeof(object)
• Object
– Data type int , float, …
– Expression a + b
Array
Will cover
later
Structure
Compile-Time Operator sizeof
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21. 21
Assuming that integers are 4 bytes and
doubles are 8 bytes.
double f;
printf("%d ",sizeof (f)); 8
printf(''%d", sizeof(int)); 4
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22. 22
sizeof(char) = 1
sizeof(short) ≤ sizeof(int) ≤ sizeof(long)
sizeof(signed)=sizeof(unsigned)=sizeof(int)
sizeof(float)
<= sizeof(double )
<= sizeof( long double)
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23. 23
Conversions
• When constants and variables of different types
are mixed in an expression, the compiler converts
all operands to the type of the largest operand-
Called Type Promotion.
- First, all char and short values are automatically
elevated to int. Called integral promotion.
- int + int = int
- short + short = int
- Arithmetic Conversion (See pg. 217)
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24. 24
char ch;
int i;
float f;
double d,result;
result= (ch / i) + (f * d) – (f + i);
int double float
double
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25. 25
• Casts - Explicit conversions.
(type) expression
If i is int:
(float) i will change expression value to
float, i is not changed.
Casts
(float) i/2
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26. 26
• Apply to an Expression:
(float) (‘c’ + 3)
• Cannot apply to an Assignment:
(int) f = 3: illegal
• As an unary operator, a cast has the same
precedence as any other unary operator.
(float) i + 3 ( (float) i ) + 3
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27. 27
/* print i and i/2 with fractions */
int main(void)
{
int i;
for(i=l; i<=100; ++i)
printf(''%d //2 is: %f
n", i, (float) i /2);
return 0;
}
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28. 28
General forms:
(int) char expression- ordinal value of char
expression
(char) int expression- character with the
ordinal value of int
expression
(int) float expression- truncates the float
expression
(float) int expression- converts int to float
(double) float exp- converts float to
doublehttp://improvec.blogspot.in