C
- Operators and data types used for programming of microcontroller 8051
C
- Operators
Operator:
Operator is symbol which is used to in arithmetic and logical operation to
perform particular task. Following are some types of operators used in
c-language.
- Arithmetic operators
- Logical operators
- Relational operators
Lets consider contents of A=12H and
B=24H for all following examples
|
Operator
symbol |
Description |
Example |
|
+ |
Addition
operation |
A+B
(Answer is 36) |
|
- |
Subtract
operation |
B-A
(Answer is 12) |
|
* |
Multiply
operation |
A*B
(Answer is 288) |
|
/ |
Division
operation |
B/A
(Answer is 2) |
|
++ |
Increment
operation |
B++
(Answer is 25) |
|
-- |
Decrement
operation |
B--
(Answer is 23) |
- Logical
operators (Bitwise): Logical operations like NOT
(compliment), AND, OR, XOR, left shift and right shift are possible using
logical operators. Following table shows symbol of operator, its working and
examples.
Lets consider contents of A=12H and
B=24H for all following examples
|
Operator
symbol |
Description |
Example |
|
~ |
Binary
NOT (1’s complement) operation |
~A
(Answer is 36) |
|
& |
Binary
AND operation |
A
& B (Answer is 0) |
|
| |
Binary
OR operation |
A
| B (Answer is 36) |
|
^ |
Binary
XOR operation |
A
^ B (Answer is 36) |
|
<< |
Binary
Left shift (by one) operation |
B
<< 1 (Answer is 48) |
|
>> |
Binary
Right shift (by one) operation |
B
>> 1 (Answer is 12) |
To
cross check logical operations, have a look at truth tables of NOT gate, AND
gate, OR gate and XOR gate.
|
NOT |
|
AND |
|
OR |
|
XOR |
||||||||
|
A |
B |
Y |
A |
B |
Y |
A |
B |
Y |
A |
B |
Y |
|||
|
0 |
- |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|||
|
1 |
- |
0 |
0 |
1 |
0 |
0 |
1 |
1 |
0 |
1 |
1 |
|||
|
|
1 |
0 |
0 |
1 |
0 |
1 |
1 |
0 |
1 |
|||||
|
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
0 |
||||||
- Relational
operations: Relational operations like equals to, not
equals to, greater than, less than, less than or equals to and greater than or
equals to are possible using logical operators. Following table shows symbol of
operator, its working and examples.
Lets consider contents of A=12H and
B=24H for all following examples
|
Operator
symbol |
Description |
Example |
|
=
= |
Check
values of A and B are equal or not |
A=
=B |
|
!= |
Check values of A and B are equal or not |
A
!= B |
|
> |
Greater than operation |
A
> B |
|
< |
Less than operation |
A
< B |
|
>= |
Greater than or equals to operation |
A
>= B |
|
<= |
Less than or equals to operation |
A
<= B |
Data
Types
- Data
types: In case of assembly language programming, only 8-bit
data type is used. If data is greater than 8-bit then it can break down into
8-bit data for processing. In case of C- language programming, there are
variable data types that can be from 1-bit to 64-bit. Data types are used to
define/declaring functions or variables. Data types can be positive or negative
i.e. signed or unsigned. Following table shows some C data types along with
their size or range
Data type
Bits
Size (Range)
bit
1
0 to 1
sbit
1
0 to 1
sfr
8
0 to 255 (RAM addresses from 80H-FF H only)
unsigned char
8
0 to 255
signed char
8
-128 to +127
unsigned int
16
0 to 65535
Sf1
16
0 to 65535
unsigned short
16
0 to 65535
signed int
16
-32768 to +32767
signed short
16
-32768 to +32767
enum
16
-32768 to +32767
unsigned long
32
0 to 4294697295
singed long
32
-2147483648 to +2147483647
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