Define void data type and write any three use of it.

Q : Define void data type and write any three use of it.

The data type void actually refers to an object that does not have a value of any type. Void is also used to indicate when a function does not return a value or no argument. Such a function is used for its side effect and not for its value. In the function declaration and definition, we have indicated that the function does not return a value by using the data type void to show an empty type, i.e. no value. Similarly, when a function has no formal parameters, the keyword void is used in the function prototype and header to signify that there is no information passed to the function.

What is dangling pointer in C? What is wild pointer in C? Give example.

Q : What is dangling pointer in C? What is wild pointer in C? Give example?

Dangling  Pointer

Dangling or wild is a pointer which does not point valid object. When a pointer has declared it must be assign a valid address memory address otherwise it will point some location which is not valid. These are special cases of memory safety violations. More generally, dangling references and wild references are references that do not resolve to a valid destination.

Void main()

{

          int *pt;

          {

                   int c=10;

                   pt=&c;

       

  }

          printf("\n\t%d",*pt);

}

Setting Combo-box Value and Display Data with VB.Net

I was working on a Brokerage Calculation project where I need to load a table’s data into combo box as in the form of value member and display member because a combo-box store two value ID which not shown at drop down list but reside in combo-box .

We need to Set/Get data through value because it’s mostly primary key and  display mode for display 

field. Take a look on following code:

Dim con As New OleDbConnection(getconstr)

Dim da As New OleDbDataAdapter(sql, con)

What are merits and demerits of array in C?

Q : What are merits and demerits of array in C?

Why we need an array.

We need array when there is a need to process more than data with similar type. For example 

• Taking marks of 10 student needs of ten integer 
• Taking name of more than one character 
• Structure record and many more

Criteria mentioned above can also be achieved through variable , but variables have following drawback which lead to use array instead of Variable.

• Each variable must has unique name which increase complexity when a large number of variables need to make. 
• Each variable load in memory at random order. So if you want to process all variable then you need to process each variable individually because allocation of space is not continuous.

For understand the above point you need to imagine a real life example.

Two close friend group decided to watch a movie and they follow two different approaches as follows

• Friends in Group one purchase ticket individually without any coordination between them for seating arrangement 
• Friend in group two book seats continuously i.e. seats no 1 to 10.

So Group two can make better communication than group one. In same way array works.

Advantage

• Continuous memory allocation.
• Process a collection of similar data type.
• Can be used to make data structure like stack,tree,queue etc.
• Easy to visit each element using index.

Disadvantage

• Static memory allocation 
• Due to static memory allocation number of element cannot be increase nor decrease at run time.
• The elements of array are stored in consecutive memory locations. So insertions and deletions are very difficult and time consuming.

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