naniroopeshmaterials.com: C-Technical Bits

PART-I:

PART-II:

C,C++ Questions
1. Base class has some virtual method and derived class has a method with the same name. If we initialize the base class pointer with derived
object,. calling of that virtual method will result in which method being called?
a. Base method
b. Derived method..
Ans. b
2. For the following C program
#define AREA(x)(3.14*x*x)
main()
{float r1=6.25,r2=2.5,a;
a=AREA(r1);
printf("\n Area of the circle is %f", a);
a=AREA(r2);
printf("\n Area of the circle is %f", a);
}
What is the output?
Ans. Area of the circle is 122.656250
Area of the circle is 19.625000
3. What do the following statements indicate. Explain.

· int(*p)[10]

· int*f()

· int(*pf)()

· int*p[10]

Refer to:
-- Kernighan & Ritchie page no. 122
-- Schaum series page no. 323
4.
void main()
{
int d=5;
printf("%f",d);
}
Ans: Undefined

5.
void main()
{
int i;
for(i=1;i<4;i++)
switch(i)
{
case 1: printf("%d",i);break;
case 2:printf("%d",i);break;
case 3:printf("%d",i);break;
}
switch(i) case 4:printf("%d",i);
}
Ans: 1,2,3,4

6.
void main()
{
char *s="\12345s\n";
printf("%d",sizeof(s));
}
Ans: 6

7.
void main()
{
unsigned i=1; /* unsigned char k= -1 => k=255; */
signed j=-1; /* char k= -1 => k=65535 */
/* unsigned or signed int k= -1 =>k=65535 */
if(i<j)
printf("less");
else
if(i>j)
printf("greater");
else
if(i==j)
printf("equal");
}
Ans: less

8.
void main()
{
float j;
j=1000*1000;
printf("%f",j);
}

1. 1000000
2. Overflow
3. Error
4. None
Ans: 4

9. How do you declare an array of N pointers to functions returning
     pointers to functions returning pointers to characters?

Ans: The first part of this question can be answered in at least
        three ways:

    1. char *(*(*a[N])())();

    2. Build the declaration up incrementally, using typedefs:

        typedef char *pc;    /* pointer to char */
        typedef pc fpc();    /* function returning pointer to char */
        typedef fpc *pfpc;    /* pointer to above */
        typedef pfpc fpfpc();    /* function returning... */
        typedef fpfpc *pfpfpc;    /* pointer to... */
        pfpfpc a[N];         /* array of... */

    3. Use the cdecl program, which turns English into C and vice
    versa:

        cdecl> declare a as array of pointer to function returning
            pointer to function returning pointer to char
        char *(*(*a[])())()

    cdecl can also explain complicated declarations, help with
    casts, and indicate which set of parentheses the arguments
    go in (for complicated function definitions, like the one
    above).
    Any good book on C should explain how to read these complicated
    C declarations "inside out" to understand them ("declaration
    mimics use").
    The pointer-to-function declarations in the examples above have
    not included parameter type information. When the parameters
    have complicated types, declarations can *really* get messy.
    (Modern versions of cdecl can help here, too.)

10. A structure pointer is defined of the type time . With 3 fields min,sec hours having pointers to intergers.
    Write the way to initialize the 2nd element to 10.

11. In the above question an array of pointers is declared.
    Write the statement to initialize the 3rd element of the 2 element to 10;

12.
int f()
void main()
{
f(1);
f(1,2);
f(1,2,3);
}
f(int i,int j,int k)
{
printf("%d %d %d",i,j,k);
}

What are the number of syntax errors in the above?

Ans: None.

13.
void main()
{
int i=7;
printf("%d",i++*i++);
}

Ans: 56

14.
#define one 0
#ifdef one
printf("one is defined ");
#ifndef one
printf("one is not defined ");

Ans: "one is defined"

15.
void main()
{
int count=10,*temp,sum=0;
temp=&count;
*temp=20;
temp=∑
*temp=count;
printf("%d %d %d ",count,*temp,sum);
}

Ans: 20 20 20

16. There was question in c working only on unix machine with pattern matching.

14. what is alloca()
Ans : It allocates and frees memory after use/after getting out of scope

17.
main()
{
static i=3;
printf("%d",i--);
return i>0 ? main():0;
}

Ans: 321

18.
char *foo()
{
char result[100]);
strcpy(result,"anything is good");
return(result);
}
void main()
{
char *j;
j=foo()
printf("%s",j);
}

Ans: anything is good.

19.
void main()
{
char *s[]={ "dharma","hewlett-packard","siemens","ibm"};
char **p;
p=s;
printf("%s",++*p);
printf("%s",*p++);
printf("%s",++*p);
}
Ans: "harma" (p->add(dharma) && (*p)->harma)
"harma" (after printing, p->add(hewlett-packard) &&(*p)->harma)
"ewlett-packard"
20. Output of the following program is
main()
{int i=0;
for(i=0;i<20;i++)
{switch(i)
case 0:i+=5;
case 1:i+=2;
case 5:i+=5;
default i+=4;
break;}
printf("%d,",i);
}
}
a) 0,5,9,13,17
b) 5,9,13,17
c) 12,17,22
d) 16,21
e) Syntax error
Ans. (d)
21. What is the ouptut in the following program
main()
{char c=-64;
int i=-32
unsigned int u =-16;
if(c>i)
{printf("pass1,");
if(c<u)
printf("pass2");
else
printf("Fail2");
}
else
printf("Fail1);
if(i<u)
printf("pass2");
else
printf("Fail2")
}
a) Pass1,Pass2
b) Pass1,Fail2
c) Fail1,Pass2
d) Fail1,Fail2
e) None of these
Ans. (c)
22. What will the following program do?
void main()
{
int i;
char a[]="String";
char *p="New Sring";
char *Temp;
Temp=a;
a=malloc(strlen(p) + 1);
strcpy(a,p); //Line number:9//
p = malloc(strlen(Temp) + 1);
strcpy(p,Temp);
printf("(%s, %s)",a,p);
free(p);
free(a);
} //Line number 15//
a) Swap contents of p & a and print:(New string, string)
b) Generate compilation error in line number 8
c) Generate compilation error in line number 5
d) Generate compilation error in line number 7
e) Generate compilation error in line number 1
Ans. (b)
23. In the following code segment what will be the result of the function,
value of x , value of y
{unsigned int x=-1;
int y;
y = ~0;
if(x == y)
printf("same");
else
printf("not same");
}
a) same, MAXINT, -1
b) not same, MAXINT, -MAXINT
c) same , MAXUNIT, -1
d) same, MAXUNIT, MAXUNIT
e) not same, MAXINT, MAXUNIT
Ans. (a)
24. What will be the result of the following program ?
char *gxxx()
{static char xxx[1024];
return xxx;
}
main()
{char *g="string";
strcpy(gxxx(),g);
g = gxxx();
strcpy(g,"oldstring");
printf("The string is : %s",gxxx());
}
a) The string is : string
b) The string is :Oldstring
c) Run time error/Core dump
d) Syntax error during compilation
e) None of these
Ans. (b)
25. Find the output for the following C program
main()
{
char *p1="Name";
char *p2;
p2=(char *)malloc(20);
while(*p2++=*p1++);
printf("%s\n",p2);
}
Ans. An empty string
26. Find the output for the following C program
main()
{
int x=20,y=35;
x = y++ + x++;
y = ++y + ++x;
printf("%d %d\n",x,y);
}
Ans. 57 94
27. Find the output for the following C program
main()
{
int x=5;
printf("%d %d %d\n",x,x<<2,x>>2);
}
Ans. 5 20 1
28 Find the output for the following C program
#define swap1(a,b) a=a+b;b=a-b;a=a-b;
main()
{
int x=5,y=10;
swap1(x,y);
printf("%d %d\n",x,y);
swap2(x,y);
printf("%d %d\n",x,y);
}
int swap2(int a,int b)
{
int temp;
temp=a;
b=a;
a=temp;
return;
}
Ans. 10 5

29 Find the output for the following C program
main()
{
char *ptr = "Ramco Systems";
(*ptr)++;
printf("%s\n",ptr);
ptr++;
printf("%s\n",ptr);
}
Ans. Samco Systems

30 Find the output for the following C program
#include<stdio.h>
main()
{
char s1[]="Ramco";
char s2[]="Systems";
s1=s2;
printf("%s",s1);
}
Ans. Compilation error giving it cannot be an modifiable 'lvalue'

31 Find the output for the following C program
#include<stdio.h>
main()
{
char *p1;
char *p2;
p1=(char *) malloc(25);
p2=(char *) malloc(25);
strcpy(p1,"Ramco");
strcpy(p2,"Systems");
strcat(p1,p2);
printf("%s",p1);
}
Ans. RamcoSystems

32. Find the output for the following C program given that
[1]. The following variable is available in file1.c
static int average_float;
Ans. All the functions in the file1.c can access the variable

33. Find the output for the following C program
# define TRUE 0
some code
while(TRUE)
{
some code
}
Ans. This won't go into the loop as TRUE is defined as 0
34. struct list{
       int x;
      struct list *next;
      }*head;

      the struct head.x =100

       Is the above assignment to pointer is correct or wrong ?
Ans. Wrong
35.What is the output of the following ?

      int i;
      i=1;
      i=i+2*i++;
      printf(%d,i);
Ans. 4
36. FILE *fp1,*fp2;

      fp1=fopen("one","w")
      fp2=fopen("one","w")
      fputc('A',fp1)
      fputc('B',fp2)
      fclose(fp1)
      fclose(fp2)
     }

     Find the Error, If Any?
Ans. no error. But It will over writes on same file.
37. What are the output(s) for the following ?
38. #include<malloc.h>
      char *f()
      {char *s=malloc(8);
      strcpy(s,"goodbye");
     }

      main()
      {
      char *f();
      printf("%c",*f()='A'); }

39. #define MAN(x,y) (x)>(y)?(x):(y)
      {int i=10;
      j=5;
      k=0;
      k=MAX(i++,++j);
      printf(%d %d %d %d,i,j,k);
      }
Ans. 10 5 0
40.
void main()
{
int i=7;
printf("%d",i++*i++);
}

Ans: 56

Write a constant declaration that declares constants to hold the number of days in a week and the number of weeks in a year. In a separate constant statement declare a constant pi as 3.1415927.

Write declaration statements to declare integer variables i and j and float variables x and y. Extend your declaration statements so that i and j are both initialised to 1 and y is initialised to 10.0.

Write C++ instructions to ask a user to type in three numbers and to read them into integer variables first, second and third.

Write C++ instructions to output the value of a variable x in a line as follows:

The value of x is ......

Write C++ instructions to generate output as follows:

A circle of radius .....

has area .....

and circumference .....

where the values of the radius, the area and the circumference are held in variables rad, area, and circum.

Correct the syntax errors in the following C++ program:

include <iostream.h>

main()

{

float x,y,z;

cout<< "Enter two numbers ";

cin >> a >> b;

cout << 'The numbers in reverse order are”<< b,a;

}

Download copy to try it.

Show the form of output displayed by the following statements when total has the value 352.74.

cout << "The final total is: " << endl;

cout << "$" << total << endl;

What data types would you use to represent the following items?

the number of students in a class

the grade (a letter) attained by a student in the class

the average mark in a class

the distance between two points

the population of a city

the weight of a postage stamp

the registration letter of a car

Write suitable declarations for variables in question 8. Be sure to choose meaningful identifiers.

->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 are the differences between malloc() and calloc()?

malloc() : allows to create memory dynamically and exact amount needed.

char *str; str = (char *) malloc(10);

calloc() : allocates main memory; allocates block bytes and clears it to zero.

char *str; str = (char *) calloc(10, sizeof(char));

What are macros? what are its advantages and disadvantages?

any function or variable that is declared along with #define.

Difference between pass by reference and pass by value?

pass by reference is passing the address of the variable which is accepted by the pointer variable..

pass by value is creating the copy of existing values and doing operations on that values, but they don’t effect the original values.

Where are the auto variables stored?

defines a local variable and has local lifetime and is used very rare.

Where does global, static, local, register variables, free memory and C Program instructions get stored?

Global variables can be used through out the program.

Static variables are used to initialise only once.

local means auto variables

Difference between arrays and linked list?

arrays is collecion of similar elements, continuous memory allocation, and dynamic memory allocation as specified by user, memory gets wasted, which allocates memory in the begining, it conatins only one datatype.

linked list creates dynamic memory in order to store the values, not continuous storageie., may or may not be, no wastage of memory. and insertion and deletion is easy in linked list, linked list contains collection of datatypes.

What are enumerations?

is to invent your own data types and define what values the variable of this datatype can take. or to define set of constants of type int. is used to clarify the operation of a program.

Describe about storage allocation and scope of global, extern, static, local and register variables?

Global storage is ordinary and scope is anywhere it can be used.

extern indicates the actual storage and initial value of the variable, or body of function, and is defined in separate code.

static storage is ordinary and can be used within a function or program, or block of code.

local is auto......

What are register variables? What are the advantage of using register variables?

What is the use of typedef?

to create user defined datatypes.

typedef int a; a b;

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?

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?

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?