• Linked Lists
     
  • How do you reverse a singly linked list? How do you reverse a doubly linked list? Write a C program to do the same. Updated!    
  • Given only a pointer to a node to be deleted in a singly linked list, how do you delete it? Updated!    
  • How do you sort a linked list? Write a C program to sort a linked list. Updated!    
  • How to declare a structure of a linked list?    
  • Write a C program to implement a Generic Linked List.    
  • How do you reverse a linked list without using any C pointers? Updated!    
  • How would you detect a loop in a linked list? Write a C program to detect a loop in a linked list.    
  • How do you find the middle of a linked list? Write a C program to return the middle of a linked list    
  • If you are using C language to implement the heterogeneous linked list, what pointer type will you use?    
  • How to compare two linked lists? Write a C program to compare two linked lists.    
  • How to create a copy of a linked list? Write a C program to create a copy of a linked list.    
  • Write a C program to free the nodes of a linked list Updated!    
  • Can we do a Binary search on a linked list?    
  • Write a C program to return the nth node from the end of a linked list. New!    
  • How would you find out if one of the pointers in a linked list is corrupted or not? New!    
  • Write a C program to insert nodes into a linked list in a sorted fashion New!    
  • Write a C program to remove duplicates from a sorted linked list New!    
  • How to read a singly linked list backwards? New!    
  • How can I search for data in a linked list? New!
     
• Write your own ....
     
  • Write your own C program to implement the atoi() function Updated!    
  • Implement the memmove() function. What is the difference between the memmove() and memcpy() function? Updated!    
  • Write C code to implement the strstr() (search for a substring) function.    
  • Write your own printf() function in C    
  • Implement the strcpy() function. Updated!    
  • Implement the strcmp(str1, str2) function. Updated!    
  • Implement the substr() function in C.    
  • Write your own copy() function    
  • Write C programs to implement the toupper() and the isupper() functions Updated!    
  • Write a C program to implement your own strdup() function.    
  • Write a C program to implement the strlen() function    
  • Write your own strcat() function New!
     
• Programs
     
  • Write a C program to swap two variables without using a temporary variable    
  • What is the 8 queens problem? Write a C program to solve it.    
  • Write a C program to print a square matrix helically.    
  • Write a C program to reverse a string Updated!    
  • Write a C program to reverse the words in a sentence in place. Updated!    
  • Write a C program generate permutations.    
  • Write a C program for calculating the factorial of a number    
  • Write a C program to calculate pow(x,n)?    
  • Write a C program which does wildcard pattern matching algorithm    
  • How do you calculate the maximum subarray of a list of numbers?    
  • How to generate fibonacci numbers? How to find out if a given number is a fibonacci number or not? Write C programs to do both.    
  • Solve the Rat In A Maze problem using backtracking.    
  • What Little-Endian and Big-Endian? How can I determine whether a machine's byte order is big-endian or little endian? How can we convert from one to another?    
  • Write C code to solve the Tower of Hanoi problem.    
  • Write C code to return a string from a function Updated!    
  • Write a C program which produces its own source code as its output    
  • Write a C progam to convert from decimal to any base (binary, hex, oct etc...)    
  • Write C code to check if an integer is a power of 2 or not in a single line?    
  • Write a C program to find the GCD of two numbers. Updated!    
  • Finding a duplicated integer problem    
  • Write code to remove duplicates in a sorted array. Updated!    
  • Find the maximum of three integers using the ternary operator.    
  • How do you initialize a pointer inside a function?    
  • Write C code to dynamically allocate one, two and three dimensional arrays (using malloc()) New!    
  • How would you find the size of structure without using sizeof()?    
  • Write a C program to multiply two matrices.    
  • Write a C program to check for palindromes.    
  • Write a C program to convert a decimal number into a binary number.    
  • Write C code to implement the Binary Search algorithm.    
  • Wite code to evaluate a polynomial.    
  • Write code to add two polynomials    
  • Write a program to add two long positive numbers (each represented by linked lists).    
  • How do you compare floating point numbers? Updated!    
  • What's a good way to implement complex numbers in C?    
  • How can I display a percentage-done indication on the screen?    
  • Write a program to check if a given year is a leap year or not?    
  • Is there something we can do in C but not in C++?    
  • How to swap the two nibbles in a byte ?    
  • How to scan a string till we hit a new line using scanf()?    
  • Write pseudocode to compare versions (like 115.10.1 vs 115.11.5).    
  • How do you get the line numbers in C?    
  • How to fast multiply a number by 7?    
  • Write a simple piece of code to split a string at equal intervals    
  • Is there a way to multiply matrices in lesser than o(n^3) time complexity?    
  • How do you find out if a machine is 32 bit or 64 bit?    
  • Write a program to have the output go two places at once (to the screen and to a file also)    
  • Write code to round numbers    
  • How can we sum the digits of a given number in single statement?    
  • Given two strings A and B, how would you find out if the characters in B were a subset of the characters in A?    
  • Write a program to merge two arrays in sorted order, so that if an integer is in both the arrays, it gets added into the final array only once. *    
  • Write a program to check if the stack grows up or down    
  • How to add two numbers without using the plus operator?    
  • How to generate prime numbers? How to generate the next prime after a given prime?    
  • Write a program to print numbers from 1 to 100 without using loops!    
  • Write your own trim() or squeeze() function to remove the spaces from a string. New!    
  • Write your own random number generator function in C.*    
  • Write your own sqrt() function in C*
     
• Trees
     
  • Write a C program to find the depth or height of a tree.    
  • Write a C program to determine the number of elements (or size) in a tree.    
  • Write a C program to delete a tree (i.e, free up its nodes)    
  • Write C code to determine if two trees are identical    
  • Write a C program to find the mininum value in a binary search tree.    
  • Write a C program to compute the maximum depth in a tree?    
  • Write a C program to create a mirror copy of a tree (left nodes become right and right nodes become left)!    
  • Write C code to return a pointer to the nth node of an inorder traversal of a BST. New!    
  • Write C code to implement the preorder(), inorder() and postorder() traversals. Whats their time complexities? Updated!    
  • Write a C program to create a copy of a tree    
  • Write C code to check if a given binary tree is a binary search tree or not?    
  • Write C code to implement level order traversal of a tree. New!    
  • Write a C program to delete a node from a Binary Search Tree?    
  • Write C code to search for a value in a binary search tree (BST).    
  • Write C code to count the number of leaves in a tree    
  • Write C code for iterative preorder, inorder and postorder tree traversals New!    
  • Can you construct a tree using postorder and preorder traversal?    
  • Construct a tree given its inorder and preorder traversal strings. Similarly construct a tree given its inorder and post order traversal strings. Updated!    
  • Find the closest ancestor of two nodes in a tree. New!    
  • Given an expression tree, evaluate the expression and obtain a paranthesized form of the expression.    
  • How do you convert a tree into an array?    
  • What is an AVL tree? Updated!    
  • How many different trees can be constructed using n nodes?    
  • A full N-ary tree has M non-leaf nodes, how many leaf nodes does it have?    
  • Implement Breadth First Search (BFS) and Depth First Search (DFS) Updated!    
  • Write pseudocode to add a new node to a Binary Search Tree (BST) Updated!    
  • What is a threaded binary tree?
     
• Bit Fiddling
     
  • Write a C program to count bits set in an integer? Updated!    
  • What purpose do the bitwise and, or, xor and the shift operators serve?    
  • How to reverse the bits in an interger?    
  • Check if the 20th bit of a 32 bit integer is on or off?    
  • How to reverse the odd bits of an integer?    
  • How would you count the number of bits set in a floating point number?*
     
• Sorting Techniques
     
  • What is heap sort?    
  • What is the difference between Merge Sort and Quick sort?    
  • Give pseudocode for the mergesort algorithm    
  • Implement the bubble sort algorithm. How can it be improved? Write the code for selection sort, quick sort, insertion sort.    
  • How can I sort things that are too large to bring into memory? New!
     
• C Pointers
     
  • What does *p++ do? Does it increment p or the value pointed by p?    
  • What is a NULL pointer? How is it different from an unitialized pointer? How is a NULL pointer defined?    
  • What is a null pointer assignment error?    
  • Does an array always get converted to a pointer? What is the difference between arr and &arr? How does one declare a pointer to an entire array?    
  • Is the cast to malloc() required at all?    
  • What does malloc() , calloc(), realloc(), free() do? What are the common problems with malloc()? Is there a way to find out how much memory a pointer was allocated?    
  • What's the difference between const char *p, char * const p and const char * const p? Updated!    
  • What is a void pointer? Why can't we perform arithmetic on a void * pointer?    
  • What do Segmentation fault, access violation, core dump and Bus error mean?    
  • What is the difference between an array of pointers and a pointer to an array?    
  • What is a memory leak?    
  • What are brk() and sbrk() used for? How are they different from malloc()?    
  • What is a dangling pointer? What are reference counters with respect to pointers?    
  • What do pointers contain?    
  • Is *(*(p+i)+j) is equivalent to p[i][j]? Is num[i] == i[num] == *(num + i) == *(i + num)?    
  • What operations are valid on pointers? When does one get the Illegal use of pointer in function error?    
  • What are near, far and huge pointers? New!    
  • What is the difference between malloc() and calloc()? New!    
  • Why is sizeof() an operator and not a function? New!    
  • What is an opaque pointer?    
  • What are the common causes of pointer bugs?
     
• C Functions
     
  • How to declare a pointer to a function?    
  • Does extern in a function declaration mean anything?    
  • How can I return multiple values from a function?    
  • Does C support function overloading?    
  • What is the purpose of a function prototype?    
  • What are inline functions?    
  • How to declare an array of N pointers to functions returning pointers to functions returning pointers to characters?    
  • Can we declare a function that can return a pointer to a function of the same type?    
  • How can I write a function that takes a variable number of arguments? What are the limitations with this? What is vprintf()?    
  • With respect to function parameter passing, what is the difference between call-by-value and call-by-reference? Which method does C use? Updated!    
  • If I have the name of a function in the form of a string, how can I invoke that function? New!    
  • What does the error, invalid redeclaration of a function mean?    
  • How can I pass the variable argument list passed to one function to another function.    
  • How do I pass a variable number of function pointers to a variable argument (va_arg) function?    
  • Will C allow passing more or less arguments than required to a function.
     
• C Statements
     
  • Whats short-circuiting in C expressions?    
  • Whats wrong with the expression a[i]=i++; ? Whats a sequence point? Updated!    
  • Does the ?: (ternary operator) return a lvalue? How can I assign a value to the output of the ternary operator?    
  • Is 5[array] the same as array[5]?    
  • What are #pragmas?    
  • What is the difference between if(0 == x) and if(x == 0)?    
  • Should we use goto or not?    
  • Is ++i really faster than i = i + 1?    
  • What do lvalue and rvalue mean?    
  • What does the term cast refer to? Why is it used?    
  • What is the difference between a statement and a block?    
  • Can comments be nested in C?    
  • What is type checking?    
  • Why can't you nest structure definitions?    
  • What is a forward reference?    
  • What is the difference between the & and && operators and the | and || operators?    
  • Is C case sensitive (ie: does C differentiate between upper and lower case letters)?    
  • Can goto be used to jump across functions?    
  • Whats wrong with #define myptr int *?    
  • What purpose do #if, #else, #elif, #endif, #ifdef, #ifndef serve?    
  • Can we use variables inside a switch statement? Can we use floating point numbers? Can we use expressions?    
  • What is more efficient? A switch() or an if() else()?    
  • What is the difference between a deep copy and a shallow copy?    
  • What is operator precedence?*
     
• C Arrays
     
  • How to write functions which accept two-dimensional arrays when the width is not known before hand?    
  • Is char a[3] = "abc"; legal? What does it mean?    
  • If a is an array, is a++ valid?    
  • How can we find out the length of an array dynamically in C?
     
• C Variables
     
  • What is the difference between the declaration and the definition of a variable?    
  • Do Global variables start out as zero?    
  • Does C have boolean variable type?    
  • Where may variables be defined in C?    
  • To what does the term storage class refer? What are auto, static, extern, volatile, const classes?    
  • What does the typedef keyword do?    
  • What is the difference between constants defined through #define and the constant keyword?    
  • What are Trigraph characters?    
  • How are floating point numbers stored? Whats the IEEE format? Updated!    
  • When should the register modifier be used? New!    
  • When should a type cast be used? New!
     
• C Structures
     
  • Can structures be assigned to variables and passed to and from functions?    
  • Can we directly compare two structures using the == operator? Updated!    
  • Can we pass constant values to functions which accept structure arguments?    
  • How does one use fread() and fwrite()? Can we read/write structures to/from files?    
  • Why do structures get padded? Why does sizeof() return a larger size?    
  • Can we determine the offset of a field within a structure and directly access that element?    
  • What are bit fields in structures? Updated!    
  • What is a union? Where does one use unions? What are the limitations of unions? New!
     
• C Macros
     
  • How should we write a multi-statement macro?    
  • How can I write a macro which takes a variable number of arguments?    
  • What is the token pasting operator and stringizing operator in C?    
  • Define a macro called SQR which squares a number. Updated!
     
• C Headers
     
  • What should go in header files? How to prevent a header file being included twice? Whats wrong with including more headers?    
  • Is there a limit on the number of characters in the name of a header file?    
  • Is it acceptable to declare/define a variable in a C header? New!
     
• C File operations
     
  • How do stat(), fstat(), vstat() work? How to check whether a file exists?    
  • How can I insert or delete a line (or record) in the middle of a file?    
  • How can I recover the file name using its file descriptor?    
  • How can I delete a file? How do I copy files? How can I read a directory in a C program?    
  • Whats the use of fopen(), fclose(), fprintf(), getc(), putc(), getw(), putw(), fscanf(), feof(), ftell(), fseek(), rewind(), fread(), fwrite(), fgets(), fputs(), freopen(), fflush(), ungetc()?    
  • How to check if a file is a binary file or an ascii file? New!
     
• C Declarations and Definitions
     
  • What is the difference between char *a and char a[]? Updated!    
  • How can I declare an array with only one element and still access elements beyond the first element (in a valid fashion)?    
  • What is the difference between enumeration variables and the preprocessor #defines?
     
• C Functions - built-in
     
  • Whats the difference between gets() and fgets()? Whats the correct way to use fgets() when reading a file?    
  • How can I have a variable field width with printf?    
  • How can I specify a variable width in a scanf() format string?    
  • How can I convert numbers to strings (the opposite of atoi)?    
  • Why should one use strncpy() and not strcpy()? What are the problems with strncpy()?    
  • How does the function strtok() work?    
  • Why do we get the floating point formats not linked error?    
  • Why do some people put void cast before each call to printf()?    
  • What is assert() and when would I use it?    
  • What do memcpy(), memchr(), memcmp(), memset(), strdup(), strncat(), strcmp(), strncmp(), strcpy(), strncpy(), strlen(), strchr(), strchr(), strpbrk(), strspn(), strcspn(), strtok() do? Updated!    
  • What does alloca() do?    
  • Can you compare two strings like string1==string2? Why do we need strcmp()?    
  • What does printf() return? New!    
  • What do setjmp() and longjump() functions do? New!
     
• C Functions - The main function
     
  • Whats the prototype of main()? Can main() return a structure?    
  • Is exit(status) equivalent to returning the same status from main()?    
  • Can main() be called recursively?    
  • How to print the arguments recieved by main()?
     
• OS Concepts
     
  • What do the system calls fork(), vfork(), exec(), wait(), waitpid() do? Whats a Zombie process? Whats the difference between fork() and vfork()?    
  • How does freopen() work? *    
  • What are threads? What is a lightweight process? What is a heavyweight process? How different is a thread from a process? *    
  • How are signals handled? *    
  • What is a deadlock? *    
  • What are semaphores? *    
  • What is meant by context switching in an OS?*    
  • What is Belady's anomaly?    
  • What is thrashing?*    
  • What are short-, long- and medium-term scheduling?    
  • What are turnaround time and response time?    
  • What is the Translation Lookaside Buffer (TLB)?    
  • What is cycle stealing?    
  • What is a reentrant program?    
  • When is a system in safe state?    
  • What is busy waiting?    
  • What is pages replacement? What are local and global page replacements?*    
  • What is meant by latency, transfer and seek time with respect to disk I/O?    
  • What are monitors? How are they different from semaphores?*    
  • In the context of memory management, what are placement and replacement algorithms?    
  • What is paging? What are demand- and pre-paging?*    
  • What is mounting?    
  • What do you mean by dispatch latency?    
  • What is multi-processing? What is multi-tasking? What is multi-threading? What is multi-programming?*    
  • What is compaction?    
  • What is memory-mapped I/O? How is it different frim I/O mapped I/O?    
  • List out some reasons for process termination.
     
• General Concepts
     
  • What is the difference between statically linked libraries and dynamically linked libraries (dll)? Updated!    
  • What are the most common causes of bugs in C?    
  • What is hashing?    
  • What do you mean by Predefined?    
  • What is data structure?    
  • What are the time complexities of some famous algorithms? Updated!    
  • What is row major and column major form of storage in matrices?    
  • Explain the BigOh notation. Updated!    
  • Give the most important types of algorithms.    
  • What is marshalling and demarshalling? New!    
  • What is the difference between the stack and the heap? Where are the different types of variables of a program stored in memory? New!    
  • Describe the memory map of a C program.    
  • What is infix, prefix, postfix? How can you convert from one representation to another? How do you evaluate these expressions?    
  • How can we detect and prevent integer overflow and underflow?*
     
• Compiling and Linking
     
  • How to list all the predefined identifiers?    
  • How the compiler make difference between C and C++?    
  • What are the general steps in compilation?    
  • What are the different types of linkages? New!    
  • What do you mean by scope and duration? New!    
  • What are makefiles? Why are they used?*
     
• HTTP
     
  • What are the basics of http? What is the difference be http and https? *
     
• ProC
     
  • How to work in ProC?
     
• Miscellaneous
     
  • Gotcha! programs New!
     
• SQL/PL-SQL/Database
     
  • Most frequently asked SQL/PL-SQL/Database questions *
     
• Unix/Linux
     
  • Most frequently asked unix questions *
     
• Quantitative Aptitude
     
  • Most frequently asked Quantitative aptitude questions*
     
• Graphs
     
  • Most frequently asked questions on Graphs*
     
• OOPs/OOAD
     
  • Most frequently asked OOPs and OOAD questions*
     
• Computer Networks
     
  • Most frequently asked questions on Computer Networks*
     
• Client Server Technologies
     
  • Most frequently asked Client - Server questions*
     
• Scripting basics
     
  • Introduction to perl New!

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Last updated: October 26, 2005