Essential Data Types in C: Your Roadmap to Mastery in 2023

C supports two categories of data types.
1) Primary Data Types
2) User defined data types in C

1) Primary Data Types

a. Integer (int)

• This holds only whole number values.
• int type consumes 2 bytes in memory.
• Its format specifier is %d for signed integers and %u for unsigned integers.
• The valid range is
  1. Signed -32768 to +32767
  2. Unsigned 0 to 65535
• Example:
  int rollno, marks;
  int rate, qty;
  int cust_ID;
  int sum=0;
• The modifier signed, unsigned, short and long can be applied to int.
• A type modifier alters the meaning of the base type to yield a new types.
  

b. Real (float)

• This holds number values with decimal places.
• float type consumes 4 bytes in memory.
• Its format specifier is %f
• The valid range for floating point number is 3.4E-38 to 3.4E+38
• Example:
  float percentage;
  float bill_amt;
  

c. Double (double)

• This holds number values with decimal places.
• double type consumes 8 bytes in memory.
• Its format specifier is %f
• The valid range for double is 1.7E-308 to 1.7E+308
• Example:
  float percentage;
  float bill_amt;
• A type modifier long can be applied to double
• The valid range for long double number is 3.4E-4932 to 3.4E+4932

d. Character (char)

• This holds only character values.
• char type consumes single byte in memory.
• Its format specifier is %c
• The valid range is
  1. Signed -128 to +127
  2. Unsigned 0 to 255
• Example:
  char status=’T’;
  

User defined data types in C / Secondary data types / User derived data types in C

• The user defined data types in C is also called as user derived data types or secondary data types.
• These are formed by combination of primary data type values
• As per google, data types constitute the semantic and characteristics of storage of data elements.
• The user defined data types in C or Secondary data types in C programming language are:
  1. Array
  2. Structure
  3. Union
  4. Enumeration
  5. Pointer
• The summary of format specifier is tabulated below:

Data Type	Format
Signed character	%c
Unsigned character	%c
Character	%c
Short signed decimal integer	%d , %i
Octal	%o
Hexadecimal	%x , %X
Exponent format	%g , %G
Short unsigned integer	%u
Integer	%d
Long integer	%ld
Float	%f
Double	%f
Long double	%lf
Always begin with + or –	+
Left justify	–

Operators with example

• Operators are used with operands in expression and assignment statement.
• According to number of operands , operators are
  1) Unary operators (one operand)
  -> ! ~ ++
  — + – * &
  2) Binary operators (two operands)
  + – * / %
  3) Ternary operators (three operands)
  ? :
• As per the type of application, operators are
  1) Arithmetic operation
  + – * / %
  2) Relational operation
  < <= > >= == !=
  3) Logical operators
  && || !
  4) Bitwise operators
  & |
  5) Assignment operators
  = += -= *= /=
  %= <<= >>= |=
  6) Shift operators
  << >>
• Following examples explain the use of some operators.
  

Example	Meaning
c=a+b;	value of addition (+) of a,b is assigned (=) to c
p=&q;	address of (&) p is assigned to pointer variable p
a<b && a<c	return non-zero if a is less than (<) b and (&&) a is less than c
r=a%b;	returns reminder i.e. modules(%) after division of a, b
a==b	compares whether a and b are equal (==). Returns true(1) if a and b are equal otherwise false (0)
a=b*c	product(*) of b, c is assigned (=) to a
*a=*b;	value at (*) b is assigned (=) to value at (*) a
a+=b	this is same as a=a+b; value of variable a is incremented by b i.e. value of a+b is assigned to variable a
a=20; b=a<<1; c=a<<2; d=a>>1;	here binary equivalent of a is 10100 left shift operator shifts all 1 to left by specified number of places. And similarly the right shift operator. b=a<<1=>101000=>b=40 c=a<<2=>1010000=>c=80 d=a>>1=>1010=>d=5 this indicates that left shift double the number and right shift half the number.
a>>=2;	this is same as a=a>>2; right shift (>>) a by 2 and assign evaluated value to variable a

Precedence and associativity of operators in C

Following table gives the rule for priority and associativity(order of evaluation) of operators in an expression.

Operators	Meaning
( )	Function call
[ ]	Array
->	Pointers to structure operator
!	Negation
~	Ones complement
++	Increment
—	Decrement
+	Unary plus
–	Unary minus
*	Value at
&	Address of
(type)	Type cast
sizeof	Size of
*	Multiplication
/	Division
%	Modules
+	Addition
–	Subtraction
<<	Left shift
>>	Right shift
<	Less than
<=	Less than or equal to
>	Greater than
>=	Greater than or equal to
==	Equal to
!=	Not equal to
&	Bitwise AND
|	Bitwise OR
&&	Logical AND
||	Logical OR
? :	Ternary / Conditional
=	Assign to
+=	Add & assign to
-=	Subtract & assign to
*=	Multiply & assign to
/=	Divide & assign to
%=	Modulo & assign to
&=	AND & assign to
|=	OR & assign to
,	Comma