• A data type specify type of the data type
  • Data types are require storing different type of value for operation purpose.
  • C- Language has the following basic data types.

[1] int (Integer):

  • Integer data type is used to store integer value without having fractional part.
  • “int” keyword is used to define integer data type variable.
  • It allocated 2 byte of memory space.
  • Example: 10,5, 25, 100,-50

[2] char (Character):

  • Character data type is used to store character data.
  • 1 byte of memory space is allocated to char data type variable.
  • “char” keyword is used to declare character data type variable.
  • It can store a signal character in 1 byte of memory space.
  • Example: ‘a’, ‘10’, ‘hello’, ‘123’

[3] float:

  • A float data type is used to store numerical value with fractional part.
  • “float” keyword is use to declare float data type variable.
  • 4 byte of memory space is allocated to it.
  • It may store positive or negative value.
  • Example:5, -0.025, 25.075

[4] double:

  • Double data type is also use to store numerical value with fractional part
  • Normally, float data type is use only for simple business calculations as it does not provide higher level of accuracy.
  • For complex calculation such as scientific or engineering were more higher level of accuracy is require, we can use double data type.
  • 8-byte of memory space is allocated to it.
  • We can use “double” keyword to declare double data type variable.

[5] long:

  • long data type is similar to double data type.
  • It offers higher level of accuracy.
  • “long”keyword is use to declare long data type variable.
       Data type Range
Char 128 to -127
Int 32767 to -32766
Float 3.4e.38 to -3.4e.37
Double 1.7e.308 to -1.7e.307

Variable (Identifier)

  • A variable is a named memory area that stores (holds) value.
  • A variable may change its value during the program execution.
  • Variable should have meaning full name.
  • they are defined using data types
  • They must follow the following naming convention rules:

Naming Convention Rules(Identifier rules):

  • First letter must be alphabet.
  • It should not be any keyword or reserved word.
  • It can be up to 32 characters long.
  • It should not contain any white space. We can use underscore (-) to join two words.
  • Name must be meaning full.