Explore topic-wise InterviewSolutions in .

The correct choice is (a) Because functions are always private

To explain I would say: The program have all of its functions VISIBLE throughout the program usually. Also, there is no specific VALUE that a function must contain. HENCE the functions are extern by DEFAULT.

Correct CHOICE is (c) There is no need to include any other HEADER FILE for definition

Explanation: When the value for the extern VARIABLE is defined with its declaration, then there is no need to include any file for the definition of the variable. The Initialization ACTS as a definition for the extern variable in the file itself.

The correct option is (a) The program can run successfully

To EXPLAIN I WOULD say: The program runs successfully. This is because only one DEFINITION of any variable is allowed. And hence the definition from the source file that is INCLUDED will be used.

The correct choice is (b) extern return_type function_name(argument_list);

Easiest explanation - The syntax must CONTAIN the keyword extern first, to DENOTE that the function is extern. Though the function are extern by default but among the given choices, it should contain the keyword, for explicit DECLARATION. Then the usual function declaration FOLLOWS.

The correct answer is (a) extern data_type variable_name;

To EXPLAIN: The syntax firstly contains the KEYWORD extern. Then the data type of the VARIABLE is GIVEN. Then the variabel name is MENTIONED by which it will be used in the program.

Correct ANSWER is (b) Definition

For EXPLANATION: The memory for the extern VARIABLES are allocated DUE to their definition. When the variables are declared, it only indicates the compiler that the variable is going to be used somewhere. But definition makes the compiler to ALLOCATE the memory for the variables.

The correct option is (b) FALSE

Best explanation: The STATEMENT is false. The variables are not EXTERN by default. If those are made extern by default, then the memory will never be ALLOCATED for those extern variables. HENCE we make the variables extern explicitly.

Right answer is (C) function is extern by DEFAULT

Best explanation: Even if we don’t specify a function to be extern, by default all the functions are exter. The COMPILER adds the keyword at the beginning of the function declaration. If there is an extern function to be USED then it will be used otherwise the new function only will be used.

The CORRECT choice is (d) Only one header file should declare it

To EXPLAIN: Only one header file should declare the EXTERN variable to be USED. There must not be more than one file declaring the same extern variable. This is to ENSURE that there is no ambiguity in using the extern variable.

Right option is (a) Only declaration of variables

The best explanation: The HEADER file only CONTAINS the declaration of variables that are extern. It doesn’t contain any static VARIABLE definitions.

The correct choice is (c) The source file must be INCLUDED in the new file

Explanation: The source file must be included in the file which NEEDS to use the EXTERN variable. This is done to ENSURE that the variables that are already declared can be used again. Only the declarations are used from one file to ANOTHER.

Correct answer is (a) Variable can be defined only once

The best explanation: The variables can be defined only once. Once the variable is defined, then it can’t be DECLARED again. The DEFINITION of a variable is ACTUAL allocation of MEMORY for the variable.

Right CHOICE is (a) Variable can be DECLARED MANY times

For explanation: The variables can be declared any number of times. There is no RESTRICTION on how many times a single variables can be declared. Declaration is just an indication that the variable will be used in the PROGRAM.

Correct choice is (B) VARIABLES to be used that are declared in another source file

Best EXPLANATION: The variables that are declared in another source file can be accessed in other FILES using extern variables. The extern variables must be mentioned explicitly. The source file is included to use its variables.

Correct choice is (d) Instance variables are initialized IMPLICITLY while AUTOMATIC are not

Explanation: The automatic variables have to be initialized EXPLICITLY. But in case of instances, those are initialized automatically during execution of the PROGRAM. The conventions are mandatory.

The correct option is (d) my

Easy explanation - The LANGUAGE perl supports local variables but the concept is BIT different. And if the values are not ASSIGNED to the local variables then it CONTAINS undef VALUE.

The CORRECT option is (a) Undefined symbol

The explanation is: If the automatic variables are used without DECLARATION or are used before the declaration then the compiler THROWS an error. The error that the symbol is undefined. The compiler MUST know everything before that can be used.

Correct choice is (d) No, java supports local VARIABLE concept

Explanation: The AUTO and register keywords are not SUPPORTED in java. Though the same is ALLOWED in java without specifying any of those keywords. The variables are local variables. But java makes it mandatory to INITIALIZE all of the local variables in a program.

Right CHOICE is (a) When execution reaches the place of declaration of automatic variables

Best explanation: Only when the execution reaches the place where the automatic variable was DECLARED, the constructor is called. This is to ensure that the memory is not allocated if not NEEDED. The memory is allocated and then destroyed as soon as it goes out of scope.

The correct OPTION is (c) Undefined/GARBAGE

The best I can explain: The automatic variable which are not initialized, contain garbage value. If we just DECLARE a variable and TRY to print its value, the RESULT is some unknown value. The value is garbage as that was not expected value.

The correct answer is (c) STACK

The best EXPLANATION: All the automatic variables are stored in a new stack entry as soon as their scope is created. If another function is called, the PRESENT data is saved in stack and new entry in stack is MADE for the called function. When the function returns, the automatic variables are used again from where those were left.

The CORRECT answer is (a) Automatic variables are invisible to called FUNCTION

The best explanation: The automatic variables are hidden from the called function. EVEN if PASSED by reference or address, the address of the variable is used and not the actual variable of calling function. Automatic variables can be const or variable.

Correct answer is (d) Is actually function or BLOCK in which it is defined

The best I can EXPLAIN: The automatic variables scope is LIMITED only WITHIN the block or the function where those are defined. This is the property of all the automatic variables.

The correct choice is (B) Are allocated and DEALLOCATED automatically

To explain I would say: The memory is allocated and deallocated automatically for the automatic variables. As SOON as the variable comes in SCOPE, the memory is allocated. The variables are destroyed as soon as those go out of scope.

The correct option is (a) Global delete OPERATOR is invoked

The best I can explain: The global delete operator is called to delete the objects that are not of class TYPE. Class type INCLUDES class, union or struct. All objects of these types can be DELETED using the global delete operator.

Right answer is (a) INVOKES function operator delete

Easiest explanation - The delete operator invokes the function operator delete. This function in TURN performs all the delete operations on the mentioned OBJECT. This is ensures safe deletion.

Right answer is (c) DELETE [] on an object and delete on object ARRAY

Explanation: The UNDEFINED result is always produced when we try to use delete [] with a single object. Because the type of deletion mismatches. Same in CASE where we try to apply delete to an object array.

Right OPTION is (a) DELETE [] objectName;

EXPLANATION: The OBJECT array that has to be deleted is mentioned after the keyword delete. But after delete, empty square brackets have to be given to denote that the deletion have to be done on array of objects.

The correct answer is (c) DELETE objectName;

EXPLANATION: The OBJECT to be deleted is mentioned after the keyword delete. This deletes the object from MEMORY and FREE up the memory that was acquired by the object.

The correct answer is (b) Only 2

Easiest EXPLANATION - There are two VARIANTS of DELETE OPERATOR. ONE is for object deletion. Other is for deletion of object array.

Correct CHOICE is (d) Its value is undefined

The explanation is: After performing delete operation on an OBJECT whole l-value is MODIFIABLE, its values BECOMES undefined. This is done so as to denote that the memory space is available to be used for other purposes.

Right choice is (b) Object destructor is called before deallocation

Best explanation: The destructor is called before the MEMORY is DEALLOCATED for any object. The destructor call initiates the DESTRUCTION process and the deallocation of memory takes place.

The correct option is (c) Can be USED on pointer with value 0

To explain: The DELETE operator can be used on pointers with the value 0. This actually means that when new operator fails and return value 0 then DELETING the result of failed new remains harmless. Hence the DELETION is possible.

The correct answer is (c) Then unpredictable ERRORS may arise

Explanation: When the DELETE OPERATOR is used with the objects that were not ALLOCATED USING new operator then unpredictable errors may arise. This is because the delete can’t perform the required actions on the type of memory allocated for the object.

Correct answer is (d) No

Explanation: The delete OPERATOR doesn’t RETURN any value. Its FUNCTION is to delete the memory allocated for an object. This is done in reverse way as that new operator WORKS.

Right option is (a) It should be DELETED USING delete operator

The best I can explain: The new operator allocates an OBJECT in memory and hence the memory ALLOCATION is bit different from usual allocation of an object. The delete operator can be used to delete the memory allocated for an object.

The correct answer is (a) Deallocates a block of memory

Explanation: The DELETE OPERATOR is the REVERSE process of a NEW operator. It deallocates all the memory ALLOCATED for an object. The object can be of any type. The delete operator completely destroys an object so that the resources can be used for other purposes.

The CORRECT answer is (a) ::operator new( sizeof( type ) )

Best EXPLANATION: The compiler implicitly converts the syntax so that the instruction can be understood by the processor and PROPER MACHINE CODE can be generated. The conversion is done implicitly and no explicit syntax is required.

The correct ANSWER is (d) Scope resolution

The best I can EXPLAIN: As USUAL, scope resolution operator is used to get the scope of parent or the global entities. Hence we can use scope resolution operator with the NEW operator to call the global new operator even if new operator is defined for the class EXPLICITLY.

The correct choice is (a) INVOKES FUNCTION operator NEW

The best I can explain: The new operator invokes function operator new. This is done to allocate the storage to an object. ::operator new is CALLED for storage allocation implicitly.

The CORRECT OPTION is (b) Are not destroyed even if they go out of scope

To explain I would SAY: It is not necessary that the objects get destroyed when they go out of scope if allocated by using NEW operator. This is because new operator RETURNS a pointer to object that it had allocated. A suitable pointer with proper scope should be defined by the programmer explicitly.

Right option is (c) INITIALIZER

Explanation: The new operator grammar is added with an initializer field. This can be USED to initialize an OBJECT with a user defined constructor. Hence can allocate memory as intended by the PROGRAMMER.

Correct answer is (C) Can’t be SPECIFIED for ARRAYS

The EXPLANATION: The initializers can’t be specified for arrays. The initializers can create arrays of object if and only if the class has a default constructor. That is a zero argument constructor so that it can be called without any argument.