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Data types - Coggle Diagram

- - - - Facts
        
        Concept of true and false
        
        Used in controlling the programming structures which relates with choice
        
        Logical data type
        
        Introduced in ALGOL 60
        
        Improves readability
        
        Also used in flags in programming
      - Value representation
        
        Single bit needed but a single addresable unit like a byte or word is used
        
        Provision is made for collection of bits in some languages
        
        False = 0 and True =1 or -1 or in general all non zero numbers(Due to the one's complement phenomena)
    - - Facts
        
        Concept of true and false
        
        Used in controlling the programming structures which relates with choice
        
        Logical data type
        
        Stored as numeric codes
        
        8 bit ASCII
        
        ISO 8859-1
        
        Unicode (16 bit)
        
        Has a single character as the value
        
        Also used in flags in programming
      - Aggregate of characters is a character set
      - Each character gets a number in a range(eg : 0-255)
      - Numbers = Code points
      - Code page = All assignments of of numbers to characters in a set
      - Collating sequence = Ordering of characters in a set is called
    - - Integers
        
        Representation
        
        Real World
        
        Why not take all numerica data as floating point numbers
        
        Computer
        
        May be supported by hardware or may be not
        
        Differences between integer data types in different languages
        
        Negative values may/maynot allowed
        
        Size vary from
        
        Depend on machine
        
        Depend on language
        
        Storage representation
        
        Unsigned
        
        Signed
        
        2s complement
        
        Sign magnitude
        
        1s compliment
        
        Operations on integer data
        
        Arithmetic
        
        Binary
        
        Unary
        
        Relation
        
        Assignment
        
        Bit Operation
      - Floating point real numbers
        
        Computer Representation
        
        Differs only from the size of domain
        
        Types
        
        Float
        
        Double
        
        Signed
        
        Represented as either fractions or exponents
        
        Hardware support depend on machine but software emulatable
        
        Representation
        
        Real world
        
        Real numbers
        
        Computer
        
        IEEE standard 754
        
        Exponent and mantissa
        
        Cons
        
        Loss of accuracy
        
        Only approximations are being given
      - Fixed point real numbers
        
        Software simulated but hardware support is present
        
        Store fixed number of decimal digits with fixed position for decimal point
        
        Data stored as
        
        BCD
        
        Integers + decimal attribute
        
        Pros
        
        High precision
        
        Cons
        
        Memory wastage
        
        Restricted range
      - Complex
        
        Descriptors
        
        Type checking and code building usage
        
        If dynamic facilitates run time
        
        Attributes + Variables
        
        Static = Only needed at compile time
        
        In some languages
        
        Allow arithmetic
        
        Floating point ordered pairs
        
        May be specified explicitly
        
        Symbol table
        
        Employed by language translator
        
        Information about declaration, type , scope level etc.
  - - - Depending on string lengths
        
        Limited dynamic string length
        
        Complex storage management needed
        
        Adjacent storage cells
        
        Fast operations
        
        Less storage
        
        Increasing string size leads to problems
        
        Pointer array
        
        Faster than linked list
        
        Require extra memory
        
        Linked List
        
        Simple allocation and deallocation
        
        Complex operations
        
        Additional storage
        
        What is kept in store?
        
        Current length
        
        Fixed maximum length
        
        A run time descriptor is required in most languages
        
        Static string length
        
        Descriptor is only needed in compile time
        
        Consists of
        
        Name of type
        
        Type length
        
        Address of first character
        
        Dynamic length strings
        
        Utilize a simple run time descriptor
        
        Has the current length stored
  - - - Facts
        
        Ordered list of distinct values which is used to assign names to integral constants
        
        Enumeration constants are typically implicitly assigned
        
        If needed can be explicitly assigned too
        
        If enumeration is not supported in languages, can be simulated wth integer values
      - Design issues
        
        Is a literal constant allowed to appear in more than one type definition?
        
        Are enumeration values coerced to integer
      - Operations possible
        
        Relational operations like equal or lessthan
        
        Assignment
        
        Successoor and predecessor due to having a order
        
        Use as loop variables
      - Pros
        
        Readability
        
        Reliability
    - - Facts
        
        Contiguos subsequence of an ordinal type
        
        Defining new names for sub versions of existing types
        
        All parent operations are inherited
        
        Exception
        
        Cannot assign values outside the specified range
      - Implementation
        
        Associate a nonnegative integer value with each symbolic constant
        
        Range checking must be implicitly included
  - - - When does allocation happen?
      - Can arrays be initialized when they have their storage allocated ?
      - What types are legal for subscripts ?
      - What is the lower bound of the subscript range and is it implicit ?
      - Are subscripting expressions in element references range checked ?
      - Problems in using parentheses to enclose array subscript
    - - Static Arrays
        
        Efficient
        
        Subscript and static storge allocation
        
        Size should be known at compilation
      - Fixed stack dynamic arrays
        
        Space efficient
        
        Storage allocation during runtime
        
        Subscript ranges are bound statically
        
        Need time to allocate and de allocate
      - Fixed heap dynamic arrays
        
        Slow due to heap
        
        Created in runtime
        
        Fixed subscript ranges and storage binding after allocation
      - Heap dynamic arrays
        
        Flexible
        
        Slow
        
        Subscript ranges and storage binding not bounded
        
        Changable size
- - - - Process Abstraction
        
        Only specifies the process rather than telling how the process performs its tasks
      - Data abstraction
        
        A high level wrap which includes only the data representation of one specific data type and the related subprograms for that type
- - - - Constructed by the programmer
      - Provided by language
      - Provided by hardware
    - - Elementary data objects
        
        Primitive : Not defined using other data types
        
        Manipulated as a unit
        
        Values stored in fixed memory space
      - Data Structures (Structured or non-scalar)
        
        Built using other data types
        
        Collection or an aggregation of data objects
        
        Storage memory space is variable
  - - - Operations : How the data object may be manipulated
      - Attributes of data object : eg-type and name
      - Values : Set of possible values for the data object
    - - Type Checking
      - Selection of correct operations when overloaded
      - Storage management
      - Storage representation