notes integerscharacters etc can be directly created and manipulated in programming languagethe responsibility of creating the structured type data items remains with the programmers themselves accordinglyprogramming languages provide mechanism to create and manipulate structured data items abstract data type (adtbefore we move to abstract data type let us understand what data type is most of the languages support basic data types viz integerrealcharacter etc at machine levelthe data is stored as strings containing ' and ' every data type interprets the string of bits in different ways and gives different results in shortdata type is method of interpreting bit patterns every data type has fixed type and range of values it can operate on for examplean integer variable can hold values between the min and max values allowed and carry out operations like additionsubtraction etc for character data typethe valid values are defined in the character set and the operations performed are like comparisonconversion from one case to another etc there are fixed operationswhich can be carried out on them we can formally define data types as formal description of the set of values and operations that variable of given type may take that was about the inbuilt data types one can also create user defined data typesdecide the range of values as well as operations to be performed on them the first step towards creating user defined data type or data structure is to define the logical properties tool to specify the logical properties of data type is abstract data type data abstraction can be defined as separation of the logical properties of the organization of programsdata from its implementation this means that it states what the data should be like it does not consider the implementation details adt is the logical picture of data typein additionthe specifications of the operations required to create and manipulate objects of this data type while defining an adtwe are not concerned with time and space efficiency or any other implementation details of the data structure adt is just useful guideline to use and implement the data type an adt has two parts value definition operation definition value definition is again divided into two parts definition clause condition clause as the name suggests the definition clause states the contents of the data type and condition clause defines any condition that applies to the data type definition clause is mandatory while condition clause is optional examplean integer variable can contain only integer values while character variable can contain only valid character value to understand the above clauses let us consider the adt representation of integer data type in the value definition the definition clause will state that it can contain any number between minimum integer value and the maximum integer value allowed by the computer while the condition clause will impose restriction saying none of the values will have decimal point lovely professional university