Data Type in C, C Operators

Posted on September 24, 2014

In the C programming language, data types refer to an extensive system used for declaring variables or functions of different types. The type of a variable determines how much space it occupies in storage and how the bit pattern stored is interpreted

The types in C can be classified as follows:

S.N.	Types and Description
1	Basic Types: They are arithmetic types and consists of the two types: (a) integer types and (b) floating-point types.
2	Enumerated types: They are again arithmetic types and they are used to define variables that can only be assigned certain discrete integer values throughout the program.
3	The type void: The type specifier void indicates that no value is available.
4	Derived types: They include (a) Pointer types, (b) Array types, (c) Structure types, (d) Union types and (e) Function types.

The array types and structure types are referred to collectively as the aggregate types. The type of a function specifies the type of the function’s return value. We will see basic types in the following section, whereas, other types will be covered in the upcoming chapters.

Integer Types

Following table gives you details about standard integer types with its storage sizes and value ranges:

Type	Storage size	Value range
char	1 byte	-128 to 127 or 0 to 255
unsigned char	1 byte	0 to 255
signed char	1 byte	-128 to 127
int	2 or 4 bytes	-32,768 to 32,767 or -2,147,483,648 to 2,147,483,647
unsigned int	2 or 4 bytes	0 to 65,535 or 0 to 4,294,967,295
short	2 bytes	-32,768 to 32,767
unsigned short	2 bytes	0 to 65,535
long	4 bytes	-2,147,483,648 to 2,147,483,647
unsigned long	4 bytes	0 to 4,294,967,295

To get the exact size of a type or a variable on a particular platform, you can use the sizeof operator. The expressions sizeof(type) yields the storage size of the object or type in bytes. Following is an example to get the size of int type on any machine:

#include<stdio.h>

#include<limits.h>

int main()

{

printf(“Storage size for int : %d \n”,sizeof(int));

return0;

}

When you compile and execute the above program it produces the following result on Linux:

Storage size for int : 4

Floating-Point Types

Following table gives you details about standard floating-point types with storage sizes and value ranges and their precision:

Type	Storage size	Value range	Precision
float	4 byte	1.2E-38 to 3.4E+38	6 decimal places
double	8 byte	2.3E-308 to 1.7E+308	15 decimal places
long double	10 byte	3.4E-4932 to 1.1E+4932	19 decimal places

The header file float.h defines macros that allow you to use these values and other details about the binary representation of real numbers in your programs. Following example will print storage space taken by a float type and its range values:

#include<stdio.h>

#include<float.h>

int main()

{

printf(“Storage size for float : %d \n”,sizeof(float));

printf(“Minimum float positive value: %E\n”, FLT_MIN );

printf(“Maximum float positive value: %E\n”, FLT_MAX );

printf(“Precision value: %d\n”, FLT_DIG );

return0;

}

When you compile and execute the above program, it produces the following result on Linux:

Storage size for float : 4

Minimum float positive value: 1.175494E-38

Maximum float positive value: 3.402823E+38

Precision value: 6

The void Type

The void type specifies that no value is available. It is used in three kinds of situations:

S.N.	Types and Description
1	Function returns as void There are various functions in C which do not return value or you can say they return void. A function with no return value has the return type as void. For example void exit (int status);
2	Function arguments as void There are various functions in C which do not accept any parameter. A function with no parameter can accept as a void. For example, int rand(void);
3	Pointers to void  A pointer of type void * represents the address of an object, but not its type. For example a memory allocation function void *malloc(size_t size ); returns a pointer to void which can be casted to any data type.

The void type may not be understood to you at this point, so let us proceed and we will cover these concepts in the upcoming chapters.

C – Operators and Expressions

• The symbols which are used to perform logical and mathematical operations in a C program are called C operators.1
• These C operators join individual constants and variables to form expressions.
• Operators, functions, constants and variables are combined together to form expressions.
• Consider the expression A + B * 5. where, +, * are operators, A, B  are variables, 5 is constant and A + B * 5 is an expression.

Types of C operators:

C language offers many types of operators. They are,

1. Arithmetic operators
2. Assignment operators
3. Relational operators
4. Logical operators
5. Bit wise operators
6. Conditional operators (ternary operators)
7. Increment/decrement operators
8. Special operators

Arithmetic Operators in C:

• C Arithmetic operators are used to perform mathematical calculations like addition, subtraction, multiplication, division and modulus in C programs.

S.no	Arithmetic Operators	Operation	Example
1	+	Addition	A+B
2	–	Subtraction	A-B
3	*	multiplication	A*B
4	/	Division	A/B
5	%	Modulus	A%B

Assignment operators in C:

• In C programs, values for the variables are assigned using assignment operators.
• For example, if the value “10″ is to be assigned for the variable “sum”, it can be assigned as “sum = 10;”
• Other assignment operators in C language are given below.

Operators		Example	Explanation
Simple assignment operator	=	sum=10	10 is assigned to variable sum
Compound assignment operators	+=	sum+=10	This_is_same_as_sum=sum+10…………
	-=	sum-=10	This is same as sum = sum-10
	*=	sum*=10	This is same as sum = sum*10
	/+	sum/=10	This is same as sum = sum/10
	%=	sum%=10	This is same as sum = sum%10
	&=	sum&=10	This is same as sum = sum&10
	^=	sum^=10	This is same as sum = sum^10

Relational operators in C:

• Relational operators are used to find the relation between two variables. i.e. to compare the values of two variables in a C program.

S.no	Operators	Example	Description
1	>	x > y	x is greater than y
2	<	x < y	x is less than y
3	>=	x >= y	x is greater than or equal to y
4	<=	x <= y	x is less than or equal to y
5	==	x == y	x is equal to y
6	!=	x != y	x is not equal to y

Logical operators in C:

• These operators are used to perform logical operations on the given expressions.
• There are 3 logical operators in C language. They are, logical AND (&&), logical OR (||) and logical NOT (!).

S.no	Operators	Name	Example	Description
1	&&	logical AND	(x>5)&&(y<5)	It returns true when both conditions are true
2	||	logical OR	(x>=10)||(y>=10)	It returns true when at-least one of the condition is true
3	!	logical NOT	!((x>5)&&(y<5))	It reverses the state of the operand “((x>5) && (y<5))” If “((x>5) && (y<5))” is true, logical NOT operator makes it false

Bit wise operators in C:

• These operators are used to perform bit operations. Decimal values are converted into binary values which are the sequence of bits and bit wise operators work on these bits.
• Bit wise operators in C language are & (bitwise AND), | (bitwise OR), ~ (bitwise OR), ^ (XOR), << (left shift) and >> (right shift).

x	y	x|y	x & y	x ^ y	Operator_symbol	Operator_name
0	0	0	0	0	&	Bitwise_AND
0	1	1	0	1	|	Bitwise OR
1	0	1	0	1	~	Bitwise_NOT
1	1	1	1	0	^	XOR
					<<	Left Shift
					>>	Right Shift

Conditional or ternary operators in C:

• Conditional operators return one value if condition is true and returns another value is condition is false.
• This operator is also called as ternary operator.

Syntax     :        (Condition? true_value: false_value);

Example :        (A > 100  ?  0  :  1);

• In above example, if A is greater than 100, 0 is returned else 1 is returned. This is equal to if else conditional statements.

C – Increment/decrement Operators

• Increment operators are used to increase the value of the variable by one and decrement operators are used to decrease the value of the variable by one in C programs.
• Example:

Increment operator :     ++ i ;    i ++ ;

Decrement operator:     – – i ;    i – – ;

Difference between pre/post increment & decrement operators in C:

• Below table will explain the difference between pre/post increment and decrement operators in C.

S.no	Operator type	Operator	Description
1	Pre increment	++i	Value of i is incremented before assigning it to variable i.
2	Post-increment	i++	Value of i is incremented after assigning it to variable i.
3	Pre decrement	– –i	Value of i is decremented before assigning it to variable i.
4	Post_decrement	i– –	Value of i is decremented after assigning it to variable i.

Special Operators in C:

• Below are some of special operators that C language offers.

S.no	Operators	Description
1	&	This is used to get the address of the variable. Example : &a will give address of a.
2	*	This is used as pointer to a variable. Example : * a  where, * is pointer to the variable a.
3	Sizeof ()	This gives the size of the variable. Example : size of (char) will give us 18u.

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