Data types, variables and Operators in Arduino.

Data types in Arduino.

Data types are the types of data which are used to create an arduino program.
Data types also define how much apace a variable will occupy in computer memory.
The following table provides all the data types which are used during Arduino programming.

Data Types in Arduino

void	Boolean	char
Unsigned char	byte	int
Unsigned int	word	long
Unsigned long	short	float
double	array	String-char array
String-object

Void- It indicates that the function is expected to return no information to the function from which it was called.
boolean (8 bit) - simple logical true/false.
char (8 bit) - signed number from -128 to 127.
unsigned char (8 bit) - same as 'byte'; if this is what you're after, you should use 'byte' instead, for reasons of clarity.
byte (8 bit) - unsigned number from 0-255
int (16 bit) - signed number from -32768 to 32767.
unsigned int (16 bit)- the same as 'word'. Use 'word' instead for clarity and brevity IDE.
word (16 bit) - unsigned number from 0-65535.
long (32 bit) - signed number from -2,147,483,648 to 2,147,483,647.
unsigned long (32 bit) - unsigned number from 0-4,294,967,295. The most common usage of this is to store the result of the millis() function, which returns the number of milliseconds the current code has been running
short- A short is a 16-bit data-type. On all Arduinos (ATMega and ARM based), a short stores a 16-bit (2-byte) value. This yields a range of -32,768 to 32,767 (minimum value of -2^15 and a maximum value of (2^15) - 1).
float (32 bit) - Data type for floating-point number is a number that has a decimal point. Floating-point numbers can be as large as 3.4028235E+38 and as low as -3.4028235E+38. They are stored as 32 bits (4 bytes) of information.
double- On the Uno and other ATMEGA based boards, Double precision floating-point number occupies four bytes. That is, the double implementation is exactly the same as the float, with no gain in precision. On the Arduino Due, doubles have 8-byte (64 bit) precision.

Variables and their Scope

The scope of variables in the C programming language, which Arduino uses, is a property. A scope is a section of the programme where variables can be defined in one of three places.

Inside a function or a block, which is called local variables.
Outside of all functions, which is called global variables.
In the definition of function parameters, which is called formal parameters.

Local variables:

Local variables are variables that are defined within a function or block.
They can only be utilized by statements that are included within that function or code block.
Local variables aren't known to have any effect outside of their own scope.
The following is an example of how to use local variables.

For Example:

Void setup () {

}

Void loop () {

int x , y ;

int z ; Local variable declaration

x = 0;

y = 0; actual initialization

z = 10;

}

Global variables:

Global variables are defined at the beginning of the programme, outside of any functions.
The value of the global variables will remain constant over the life of your programme.
Any function has access to a global variable. That is, once a global variable is declared, it is available for use throughout your entire programme.

For Examples:

Int T , S ;

float c = 0 ; Global variable declaration

Void setup () {

}

Void loop () {

int x , y ;

int z ; Local variable declaration

x = 0;

y = 0; actual initialization

z = 10;

}

Operators in Arduino:

A symbol that directs the compiler to execute certain mathematical or logical tasks is known as an operator.
The C language has a large number of built-in operators, including the following:

Arithmetic Operators.
Comparison Operators.
Boolean Operators.
Bitwise Operators.
Compound Operators.

Operators in Arduino

1. Arithmetic Operators

Assume variable A holds 20 and variable B holds 40 then −

Operator name	Operator simple	Description	Example
Assignment operator	=	Stores the value to the right of the equal sign in the variable to the left of the equal sign.	A = B
Addition	+	Adds two operands	A + B will give 60
Subtraction	-	Subtracts second operand from the first	A - B will give -20
Multiplication	*	Multiply both operands	A * B will give 800
Division	/	Divide numerator by denominator	B / A will give 2
Modulo	%	Modulus Operator and remainder of after an integer division	B % A will give 0

Example:

void loop () {

int a = 9,b = 4,c;

c = a + b;

c = a - b;

c = a * b;

c = a / b;

c = a % b;

}

Expected Output:

a + b = 13

a - b = 5

a * b = 36

a / b = 2

Remainder when a divided by b = 1

2. Comparison Operators:

Assume variable A holds 10 and variable B holds 20 then −

Operator name	Operator simple	Description	Example
Equal to	= =	Checks if the value of two operands is equal or not, if yes then condition becomes true.	(A == B) is not true
Not equal to	! =	Checks if the value of two operands is equal or not, if values are not equal then condition becomes true.	(A != B) is true
Less than	<	Checks if the value of left operand is less than the value of right operand, if yes then condition becomes true.	(A < B) is true
Greater than	>	Checks if the value of left operand is greater than the value of right operand, if yes then condition becomes true.	(A > B) is not true
Less than or equal to	< =	Checks if the value of left operand is less than or equal to the value of right operand, if yes then condition becomes true.	(A <= B) is true
Greater than or equal to	> =	Checks if the value of left operand is greater than or equal to the value of right operand, if yes then condition becomes true.	(A >= B) is not true

Example:

void loop () {

int a = 9,b = 4

bool c = false;

if(a == b)

c = true;

else

c = false;

if(a != b)

c = true;

else

c = false;

if(a < b)

c = true;

else

c = false;

if(a > b)

c = true;

else

c = false;

if(a <= b)

c = true;

else

c = false;

if(a >= b)

c = true;

else

c = false;

}

Expected Output:

c = false

c = true

c = false

c = true

c = false

3. Boolean Operators:

Assume variable A holds 10 and variable B holds 20 then −

Operator name	Operator simple	Description	Example
and	&&	Called Logical AND operator. If both the operands are non-zero then then condition becomes true.	(A && B) is true
or	\|\|	Called Logical OR Operator. If any of the two operands is non-zero then then condition becomes true.	(A \|\| B) is true
not	!	Called Logical NOT Operator. Use to reverses the logical state of its operand. If a condition is true then Logical NOT operator will make false.	!(A && B) is false

Example:

void loop () {

int a = 9,b = 4

bool c = false;

if((a > b)&& (b < a))

c = true;

else

c = false;

if((a == b)|| (b < a))

c = true;

else

c = false;

if( !(a == b)&& (b < a))

c = true;

else

c = false;

}

Expected Output:

c = true

4. Bitwise Operators:

Assume variable A holds 60 and variable B holds 13 then −

Operator name	Operator simple	Description	Example
and	&	Binary AND Operator copies a bit to the result if it exists in both operands.	(A & B) will give 12 which is 0000 1100
or	\|	Binary OR Operator copies a bit if it exists in either operand	(A \| B) will give 61 which is 0011 1101
xor	^	Binary XOR Operator copies the bit if it is set in one operand but not both.	(A ^ B) will give 49 which is 0011 0001
not	~	Binary Ones Complement Operator is unary and has the effect of 'flipping' bits.	(~A ) will give -60 which is 1100 0011
shift left	<<	Binary Left Shift Operator. The left operands value is moved left by the number of bits specified by the right operand.	A << 2 will give 240 which is 1111 0000
shift right	>>	Binary Right Shift Operator. The left operands value is moved right by the number of bits specified by the right operand.	A >> 2 will give 15 which is 0000 1111

Example:

void loop () {

int a = 10,b = 20

int c = 0;

c = a & b ;

c = a | b ;

c = a ^ b ;

c = a ~ b ;

c = a << b ;

c = a >> b ;

}

Expected Output:

c = 12

c = 61

c = 49

c = -60

c = 240

c = 15

5. Compound Operators:

Assume variable A holds 10 and variable B holds 20 then −

Operator name	Operator simple	Description	Example
increment	++	Increment operator, increases integer value by one	A++ will give 11
decrement	--	Decrement operator, decreases integer value by one	A-- will give 9
compound addition	+=	Add AND assignment operator. It adds right operand to the left operand and assign the result to left operand	B += A is equivalent to B = B+ A
compound subtraction	-=	Subtract AND assignment operator. It subtracts right operand from the left operand and assign the result to left operand	B -= A is equivalent to B = B - A
compound multiplication	*=	Multiply AND assignment operator. It multiplies right operand with the left operand and assign the result to left operand	B= A is equivalent to B = B A
compound division	/=	Divide AND assignment operator. It divides left operand with the right operand and assign the result to left operand	B /= A is equivalent to B = B / A
compound modulo	%=	Modulus AND assignment operator. It takes modulus using two operands and assign the result to left operand	B %= A is equivalent to B = B % A
compound bitwise or	\|=	bitwise inclusive OR and assignment operator	A \|= 2 is same as A = A \| 2
compound bitwise and	&=	Bitwise AND assignment operator	A &= 2 is same as A = A & 2

Example:

void loop () {

int a = 10,b = 20

int c = 0;

a++;

a--;

b += a;

b -= a;

b *= a;

b /= a;

a %= b;

a |= b;

a &= b;

}

Expected Output:

a = 11

a = 9

b = 30

b = 10

b = 200

b = 2

a = 0

a = 30

Data types, variables and Operators in Arduino.

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