Latest Technical Interview Answers - 2

Latest Technical Interview Answers - 2

What are the standard predefined macros?
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The ANSI C standard defines six predefined macros for use in the C language: Macro Name Purpose _ _LINE_ _ Inserts the current source code line number in your code. _ _FILE_ _ Inserts the current source code filename in your code. _ _ Inserts the current date of compilation in your code. _ _TIME_ _ Inserts the current time [...]
What is the stack?
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The stack is where all the functions’ local (auto) variables are created. The stack also contains some information used to call and return from functions. A stack trace is a list of which functions have been called, based on this information. When you start using a debugger, one of the first things you should learn is [...]
When should the register modifier be used? Does it really help?
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The register modifier hints to the compiler that the variable will be heavily used and should be kept in the CPU’s registers, if possible, so that it can be accessed faster. There are several restrictions on the use of the register modifier. First, the variable must be of a type that can be held in the CPU’s [...]
when should the volatile modifier be used?
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The volatile modifier is a directive to the compiler’s optimizer that operations involving this variable should not be optimized in certain ways. There are two special cases in which use of the volatile modifier is desirable. The first case involves memory-mapped hardware (a device such as a graphics adaptor that appears to the computer’s hardware [...]
What is the quickest sorting method to use?
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The answer depends on what you mean by quickest. For most sorting problems, it just doesn’t matter how quick the sort is because it is done infrequently or other operations take significantly more time anyway. Even in cases in which sorting speed is of the essence, there is no one answer. It depends on not [...]
What is the result of using Option Explicit?
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When writing your C program, you can include files in two ways. The first way is to surround the file you want to include with the angled brackets < and >. This method of inclusion tells the preprocessor to look for the file in the predefined default location. This predefined default location is often an INCLUDE environment variable [...]
Write a program to interchange 2 variables without using the third one
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. a=7; b=2; a = a + b; b = a - b; a = a - b;
How can method defined in multiple base classes with same name can be invoked from derived class simultaneously
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ex: class x { public: m1(); }; class y { public: m1(); }; class z :public x, public y { public: m1() { x::m1(); y::m1(); } };
Difference between const char* p and char const* p
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in const char* p, the character pointed by ‘p’ is constant, so u cant change the value of character pointed by p but u can make ‘p’ refer to some other location. in char const* p, the ptr ‘p’ is constant not the character referenced by it, so u cant make ‘p’ to reference to any [...]
Does there exist any other function which can be used to convert an integer or a float to a string?
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Some implementations provide a nonstandard function called itoa(), which converts an integer to string. #include char *itoa(int value, char *string, int radix); DEscriptION The itoa() function constructs a string representation of an integer. PARAMETERS value: Is the integer to be converted to string representation. string: Points to the buffer that is to hold resulting string. The resulting string may be as long as seventeen bytes. radix: Is [...]
Which bit wise operator is suitable for putting on a particular bit in a number?
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The bitwise OR operator. In the following code snippet, the bit number 24 is turned ON: some_int = some_int | KBit24;
Which bit wise operator is suitable for checking whether a particular bit is on or off?
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The bitwise AND operator. Here is an example:enum { KBit0 = 1, KBit1, … KBit31, }; if ( some_int & KBit24 ) printf ( “Bit number 24 is ON\n” ); else printf ( “Bit number 24 is OFF\n” ); Which bit wise operator is suitable for turning off a particular bit in a number? The bitwise AND operator, again. In the following code snippet, the bit [...]
What is the difference between strings and character arrays?
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A major difference is: string will have static storage duration, whereas as a character array will not, unless it is explicity specified by using the static keyword. Actually, a string is a character array with following properties: * the multibyte character sequence, to which we generally call string, is used to initialize an array of static storage [...]
What will be printed as the result of the operation below:
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main() { int x=10, y=15; x = x++; y = ++y; printf(“%d %d\n”,x,y); } Answer: 11, 16
Compilation How to reduce a final size of executable?
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Size of the final executable can be reduced using dynamic linking for libraries. Linked Lists — Can you tell me how to check whether a linked list is circular? Create two pointers, and set both to the start of the list. Update each as follows: while (pointer1) { pointer1 = pointer1->next; pointer2 = pointer2->next; if (pointer2) pointer2=pointer2->next; if (pointer1 == pointer2) { print [...]
What is the difference between “calloc(…)” and “malloc(…)”?
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1. calloc(…) allocates a block of memory for an array of elements of a certain size. By default the block is initialized to 0. The total number of memory allocated will be (number_of_elements * size). malloc(…) takes in only a single argument which is the memory required in bytes. malloc(…) allocated bytes of memory and not [...]
What is the output of printf(”%d”)?
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1. When we write printf(”%d”,x); this means compiler will print the value of x. But as here, there is nothing after %d so compiler will show in output window garbage value. 2. When we use %d the compiler internally uses it to access the argument in the stack (argument stack). Ideally compiler determines the offset of [...]
What is a null pointer?
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There are times when it’s necessary to have a pointer that doesn’t point to anything. The macro NULL, defined in , has a value that’s guaranteed to be different from any valid pointer. NULL is a literal zero, possibly cast to void* or char*. Some people, notably C++ programmers, prefer to use 0 rather than [...]
Can include files be nested?
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Answer Yes. Include files can be nested any number of times. As long as you use precautionary measures , you can avoid including the same file twice. In the past, nesting header files was seen as bad programming practice, because it complicates the dependency tracking function of the MAKE program and thus slows down compilation. [...]
Can a variable be both const and volatile?
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Yes. The const modifier means that this code cannot change the value of the variable, but that does not mean that the value cannot be changed by means outside this code. For instance, in the example in FAQ 8, the timer structure was accessed through a volatile const pointer. The function itself did not change [...]