Programming languages | Practice Questions

Multiple choice technology programming languages

I have a function declaration like this(in C/C++).const int f(int* a){ ..... // Do something here return *a; }what is the purpose of the keyword const here?

It is just a fancy keyword, No purpose here
Prevents the compiler from assigning the function as an rvalue
Prevents the compiler from assigning the function as an lvalue
It makes sure that the return value is a const and is not changed by anyone else

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Multiple choice technology programming languages

A friend of mine once wrote a function as follows. int * func() { int i; for (int k=0;k<200;k++) //Do something here .... return &i; } I think it is faulty . What is wrong here?

Nothing is wrong. You are wrong.
Loops are not allowed inside the function scope, Since it degrades performance
My friend tried to return a pointer to a local function variable , which is invalid once the function call compltes.
The value i is not properly initialised, SO it may contain some garbage .

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Multiple choice technology programming languages

I want to declare a pointer to a constant int variable ,pointing to a constant memory location. What is the syntax?

const int* ptr
const* int ptr
There is no such declaration like that
const int* const ptr

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Multiple choice technology programming languages

void vp; char c; int i=20; float f=30.00; pick the line which will cause an error in a C++ compiler

vp=&f;
c=(char*)&i;
c=vp;
*i++;
f++;

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Multiple choice technology programming languages

consider the following line in the c++ code extern "C" { f1(); f2();... } The purpose of the extern keyword is

They tell the C++ compiler that they are functions compiled by a C compiler , So that they can be used in C++
they mean that the function are declared somewhere and defined somewhere
They improve performance
They are used with extern variables.

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Multiple choice technology programming languages

A ( hypothetical ;) ) graphics program uses the following structure to represet a 3d point struct point3d { int x; int y; int z; // X,y,z represent the three cooddinates of a 3d point in space }; A function was written to calculate the distace between two point3d objects. void func(point3d pt1,point3d pt2) { // Calculate the distance ..... } say at run time 2 million point3d struct objects were created and the above mentioned function was called say 1 million times. Calling the above mentioned function will result in a performance hit because

The point3d is represented as struct . change it to a class and it will run better
The point3d struct is not byte aligned.
The in the function point3d struct parameters are passed by value, Which will cause additional overhead.
The point3d struct has 3 members of type int . Change it to short ,the program will run faster.

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Multiple choice technology programming languages

public static void main(String[] args){ Integer i = new Integer(5); List myList; myList = new ArrayList(); myList.add(3); myList.add(5); myList.add(7); myList.remove(i); for(String s: myList) { System.out.println("List Value >> "+s); } } What is the output?

3,7
3,5,7
index Outofbound exception
Compilation fails

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Multiple choice technology programming languages

3,7
3,5,7
index Outofbound exception
Compilation fails

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Multiple choice technology programming languages

class A{ public void _a(){ System.out.println("A"); } } class B extends A{ public void _a(){ System.out.println("B"); } } public class InheritanceTest { public static void main(String[] args){ A aa = new B(); System.out.println(aa._a()); } } What is the output?

B
A
Compilation fails
none of these

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Multiple choice technology programming languages

class B1{ public B1(){ System.out.println("B"); } } class A1 extends B1{ void A1(){ System.out.println("A"); } } public class Test { public static void main(String[] args){ B1 a = new A1(); } } what will be output?

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