(Interview) Important Interview Questions On Object Oriented Programming Concepts

Important Interview Questions On Object Oriented Programming Concepts

  • How do you write a program which produces its own source code as its output?
  • How can I find the day of the week given the date?
  • Why doesn't C have nested functions?
  • What is the most efficient way to count the number of bits which are set in a value?
  • How can I convert integers to binary or hexadecimal?
  • How can I call a function, given its name as a string?
  • How do I access command-line arguments?
  • How can I return multiple values from a function?
  • How can I invoke another program from within a C program?
  • How can I access memory located at a certain address?
  • How can I allocate arrays or structures bigger than 64K?
  • How can I find out how much memory is available?
  • How can I read a directory in a C program?
  • How can I increase the allowable number of simultaneously open files?
  • What's wrong with the call "fopen("c:\newdir\file.dat", "r")"?
  • What is the output of printf("%d")
  • What will happen if I say delete this
  • Difference between "C structure" and "C++ structure".
  • Diffrence between a "assignment operator" and a "copy constructor"
  • What is the difference between "overloading" and "overridding"?
  • Explain the need for "Virtual Destructor".
  • Can we have "Virtual Constructors"?
  • What are the different types of polymorphism?
  • What are Virtual Functions? How to implement virtual functions in "C"
  • What are the different types of Storage classes?
  • What is Namespace?
  • What are the types of STL containers?.
  • Difference between "vector" and "array"?
  • How to write a program such that it will delete itself after exectution?
  • Can we generate a C++ source code from the binary file?
  • What are inline functions?
  • Talk sometiming about profiling?
  • How many lines of code you have written for a single program?
  • What is "strstream" ?
  • How to write Multithreaded applications using C++?
  • Explain "passing by value", "passing by pointer" and "passing by reference"
  • Write any small program that will compile in "C" but not in "C++"
  • Have you heard of "mutable" keyword?
  • What is a "RTTI"?
  • Is there something that I can do in C and not in C++?
  • Why preincrement operator is faster than postincrement?
  • What is the difference between "calloc" and "malloc"?
  • What will happen if I allocate memory using "new" and free it using "free" or allocate sing "calloc" and free it using "delete"?
  • What is Memory Alignment?
  • Explain working of printf.
  • Difference between "printf" and "sprintf".
  • What is "map" in STL?
  • When shall I use Multiple Inheritance?
  • What are the techniques you use for debugging?
  • How to reduce a final size of executable?
  • Give 2 examples of a code optimization.
  • What is inheritance?
  • Difference between Composition and Aggregation.
  • Difference: Sequence Diagrams, Collaboration Diagrams.
  • Difference: 'uses', 'extends', 'includes'
  • What shall I go for Package Diagram?
  • What is Polymorphism?
  • Is class an Object? Is object a class?
  • Comment: C++ "includes" behavior and java "imports"
  • What do you mean by "Realization"?
  • What is a Presistent, Transient Object?
  • What is the use of Operator Overloading?
  • Does UML guarantee project success?
  • Difference: Activity Diagram and Sequence Diagram.
  • What is association?
  • How to resolve many to many relationship?
  • How do you represent static members and abstract classes in Class Diagram?
  • What does static variable mean?
  • What is a pointer?
  • What is a structure?
  • What are the differences between structures and arrays?
  • In header files whether functions are declared or defined? 
  • What are the differences between malloc() and calloc()?
  • What are macros? what are its advantages and disadvantages?
  • Difference between pass by reference and pass by value?
  • What is static identifier?
  • Where are the auto variables stored?
  • Where does global, static, local, register variables, free memory and C Program instructions get stored?
  • Difference between arrays and linked list?
  • What are enumerations?
  • Describe about storage allocation and scope of global, extern, static, local and register variables?
  • What are register variables? What are the advantage of using register variables?
  • What is the use of typedef?
  • Can we specify variable field width in a scanf() format string? If possible how?
  • Out of fgets() and gets() which function is safe to use and why?
  • Difference between strdup and strcpy?
  • What is recursion?
  • Differentiate between a for loop and a while loop? What are it uses?
  • What are the different storage classes in C?
  • Write down the equivalent pointer expression for referring the same element a[i][j][k][l]?
  • What is difference between Structure and Unions?
  • What the advantages of using Unions?
  • What are the advantages of using pointers in a program?
  • What is the difference between Strings and Arrays?
  • In a header file whether functions are declared or defined?
  • What is a far pointer? where we use it?
  • How will you declare an array of three function pointers where each function receives two ints and returns a float?
  • what is a NULL Pointer? Whether it is same as an uninitialized pointer?
  • What is a NULL Macro? What is the difference between a NULL Pointer and a NULL Macro?
  • What does the error 'Null Pointer Assignment' mean and what causes this error?
  • What is near, far and huge pointers? How many bytes are occupied by them?
  • How would you obtain segment and offset addresses from a far address of a memory location?
  • Are the expressions arr and &arr same for an array of integers?
  • Does mentioning the array name gives the base address in all the contexts?
  • Explain one method to process an entire string as one unit?
  • What is the similarity between a Structure, Union and enumeration?
  • Can a Structure contain a Pointer to itself?
  • How can we check whether the contents of two structure variables are same or not?
  • How are Structure passing and returning implemented by the complier?
  • How can we read/write Structures from/to data files?
  • What is the difference between an enumeration and a set of pre-processor # defines?
  • what do the 'c' and 'v' in argc and argv stand for?
  • Are the variables argc and argv are local to main?
  • What is the maximum combined length of command line arguments including the space between adjacent arguments?
  • If we want that any wildcard characters in the command line arguments should be appropriately expanded, are we required to make any special provision? If yes, which?
  • Does there exist any way to make the command line arguments available to other functions without passing them as arguments to the function?
  • What are bit fields? What is the use of bit fields in a Structure declaration?
  • To which numbering system can the binary number 1101100100111100 be easily converted to?
  • Which bit wise operator is suitable for checking whether a particular bit is on or off?
  • Which bit wise operator is suitable for turning off a particular bit in a number?
  • Which bit wise operator is suitable for putting on a particular bit in a number?
  • Which bit wise operator is suitable for checking whether a particular bit is on or off?
  • which one is equivalent to multiplying by 2:Left shifting a number by 1 or Left shifting an unsigned int or char by 1?
  • Write a program to compare two strings without using the strcmp() function.
  • Write a program to concatenate two strings.
  • Write a program to interchange 2 variables without using the third one.
  • Write programs for String Reversal & Palindrome check
  • Write a program to find the Factorial of a number
  • Write a program to generate the Fibinocci Series
  • Write a program which employs Recursion
  • Write a program which uses Command Line Arguments
  • Write a program which uses functions like strcmp(), strcpy()? etc
  • What are the advantages of using typedef in a program?
  • How would you dynamically allocate a one-dimensional and two-dimensional array of integers?
  • How can you increase the size of a dynamically allocated array?
  • How can you increase the size of a statically allocated array?
  • When reallocating memory if any other pointers point into the same piece of memory do you have to readjust these other pointers or do they get readjusted automatically?
  • Which function should be used to free the memory allocated by calloc()?
  • How much maximum can you allocate in a single call to malloc()?
  • Can you dynamically allocate arrays in expanded memory?
  • What is object file? How can you access object file?
  • Which header file should you include if you are to develop a function which can accept variable number of arguments?
  • Can you write a function similar to printf()?
  • How can a called function determine the number of arguments that have been passed to it?
  • Can there be at least some solution to determine the number of arguments passed to a variable argument list function?
  • How do you declare the following:
  • An array of three pointers to chars
  • An array of three char pointers
  • A pointer to array of three chars
  • A pointer to function which receives an int pointer and returns a float pointer
  • A pointer to a function which receives nothing and returns nothing
  • What do the functions atoi(), itoa() and gcvt() do?
  • Does there exist any other function which can be used to convert an integer or a float to a string?
  • How would you use qsort() function to sort an array of structures?
  • How would you use qsort() function to sort the name stored in an array of pointers to string?
  • How would you use bsearch() function to search a name stored in array of pointers to string?
  • How would you use the functions sin(), pow(), sqrt()?
  • How would you use the functions memcpy(), memset(), memmove()?
  • How would you use the functions fseek(), freed(), fwrite() and ftell()?
  • How would you obtain the current time and difference between two times?
  • How would you use the functions randomize() and random()?
  • How would you implement a substr() function that extracts a sub string from a given string?
  • What is the difference between the functions rand(), random(), srand() and randomize()?
  • What is the difference between the functions memmove() and memcpy()?
  • How do you print a string on the printer?
  • Can you use the function fprintf() to display the output on the screen?
  • What is an object?
  • What is the difference between an object and a class?
  • What is the difference between class and structure?
  • What is public, protected, private?
  • What are virtual functions?
  • What is friend function?
  • What is a scope resolution operator?
  • What do you mean by inheritance?
  • What is abstraction?
  • What is polymorphism? Explain with an example.
  • What is encapsulation?
  • What do you mean by binding of data and functions?
  • What is function overloading and operator overloading?
  • What is virtual class and friend class?
  • What do you mean by inline function?
  • What do you mean by public, private, protected and friendly?
  • When is an object created and what is its lifetime?
  • What do you mean by multiple inheritance and multilevel inheritance? Differentiate between them.
  • Difference between realloc() and free?
  • What is a template?
  • What are the main differences between procedure oriented languages and object oriented languages?
  • What is R T T I ?
  • What are generic functions and generic classes?
  • What is namespace?
  • What is the difference between pass by reference and pass by value?
  • Why do we use virtual functions?
  • What do you mean by pure virtual functions?
  • What are virtual classes?
  • Does c++ support multilevel and multiple inheritance?
  • What are the advantages of inheritance?
  • When is a memory allocated to a class?
  • What is the difference between declaration and definition?
  • What is virtual constructors/destructors?
  • In c++ there is only virtual destructors, no constructors. Why?
  • What is late bound function call and early bound function call? Differentiate.
  • How is exception handling carried out in c++?
  • When will a constructor executed?
  • What is Dynamic Polymorphism?
  • Write a macro for swapping integers.


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