Monday 4 November 2013

Aptitude Formulas



There are certain areas of quantitative aptitude such as numbers, time and work, trains that can be solved easily with the help of simple formulas. 

You can find a list of such handy shortcut formulas below, that will be helpful to crack quants part in aptitude exams. Totally 22 topics are covered in the list of formulas.


You can download the formulas as a PDF file from here :

Formulas.pdf

(Alternative link)

Formulas.pdf

(Please inform if link is dead)





Wednesday 2 October 2013

Accessor



Hi guys.. I have created a small software by myself that works on Windows OS. Its my 1st try. Have a look at it ..


This software, Accessor, alters the accessability (Permission) to a folder. You can make a folder accessable or unaccessable using this software.


If the folder is made unaccessable, then cut, copy, paste, delete or shift+del operations wont be effective with that folder. It cannot be opened.

Sometimes Viruses create such problems in your system. You can restore those folders to normal state using this software.


This process is completely reversable. It can be used to hide your data from others. You can also use this to retrieve your data that are made unaccessable by viruses. Or you can just make fun ;)


Before making unaccessable (Just a normal folder) :




After making Unaccessable using the Accessor software :



You can see the difference in Size and No of files and folders .


This is what happens when you try to open the folder :

After making Accessable using the Accessor software :
 


And your folder is back as it was.

As you see, your folder becomes completely safe. Safe from everyone including a variety of viruses.


Reviews and Comments are most welcomed. If you have any questions, feel free to ask. Hope you guys enjoy using Accessor.


NOTE :

1. Don't use this software to lock C:\Windows or C:\Program Files. The results may be undesirable effects.


2. 'Run As Administrator' for better performance. 


3. Since it works with some Administrator level options, Some Antivirus program might consider this as Virus. Don't worry, Its completely Safe.


(The links have been updated to version 2 of Accessor. To know what is new in version 2, click here.)


You can download the software free of cost from here :
  

Alternative Link :


(Please inform if the link is dead) 


 

Saturday 31 August 2013

C - Aptitude - 1



Some C Aptitude questions that are often questioned in interviews are listed below.
You can find the answers at the bottom of the page.



Questions :
1. What can be said of the following program  ?
          main()
             {
                enum Months {JAN =1,FEB,MAR,APR};
                Months X = JAN;
                if(X==1)
                   {
                     printf("Jan is the first month");                                                              
                  }
             }
          a) Does not print anything
          b) Prints : Jan is the first month
          c) Generates compilation error
          d) Results in runtime error



2.main()
{
            extern int i;
            i=20;
printf("%d",i);
}
a) 20
        b) Garbage Value
        c) Compilation error
        d) Linker error


                       

3.         enum colors {BLACK,BLUE,GREEN}
 main()
{
 
 printf("%d..%d..%d",BLACK,BLUE,GREEN);
  
 return(1);
}
a) 5..4..5
b) Garbage Value
c) 0..1..2
d) Error





  4. Given the following statement enum day = { jan = 1 ,feb=4, april, may} What is the value of may?
      (a) 4
      (b) 5
      (c) 6
      (d) 11
      (e) None of the above




5. What is the output of the following program?
                 main()
                        {
                          int l=6;
                          switch(l)
                          { default : l+=2;
                            case 4: l=4;                                                                           
                            case 5: l++;
                            break;
                            }
                            printf("%d",l);                                                                                      
                              }
                    a)8 b)6 c)5 d)4 e)none


6.       main()
{
            int i=3;
            switch(i)
             {
                default:printf("zero");
                case 1: printf("one");
                           break;
               case 2:printf("two");
                          break;
              case 3: printf("three");
                          break;
              } 
}
a) zero
b) three
c) Compiler error
d) Runtime error





7.         #include<stdio.h>
main()
{
int i=1,j=2;
switch(i)
 {
 case 1:  printf("GOOD");
                break;
 case j:  printf("BAD");
               break;
 }
}
a) GOOD
b) BAD
c) Compiler error
d) Runtime error





8.         main()
{
                        float i=1.5;
            switch(i)
                        {
                        case 1: printf("1");
                                    case 2: printf("2");
                                    default : printf("0");
            }
}
a) 1
b) 0
c) Compiler error
d) Runtime error



                      

9. 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







10. main()
 {
 int i;
 for(i=0;i<3;i++)
 switch(i)
 {
 case 1: printf("%d",i);
 case 2 : printf("%d",i);
 default: printf("%d"i);
 }
 }
a) 0111222
b) Error
c)012
d)011122




11.  what is printed when the following program is compiled and executed?
           int    func (int x)
              {
                if (x<=0)
            return(1);
            return func(x -1) +x;                                                                                                 
              }
              main()
                    {
                       printf("%d\n",func(5));
                     }
            a) 12
            b) 16
            c) 15
            d) 11


 

12. What is the output of the following program?
            main()
                   {
                    int x=20;
                    int y=10;
                    swap(x,y);
                    printf("%d %d",y,x+2);
                  }
                     swap(int x,int y)
                             {
                               int temp;
                               temp =x;
                               x=y;
                                y=temp;
                             }
                
a)       10,20 b) 20,12 c) 22,10 d)10,22 e)none




13. Which of the following about the following two declaration is true
       i ) int *F()
       ii) int (*F)()
 Choice :
      a) Both are identical
      b) The first is a correct declaration and the second is wrong
      c) The first declaraion is a function returning a pointer to an integer and the second is a pointer to            function returning int
      d) Both are different ways of declarin pointer to a function   




 14. main()
{
        printf("%p",main);
}
a) Compiler error
b) Stack Overflow
c) Some address will be printed
d) Garbage value printed recursively



          

15.        main()
{
clrscr();
}
clrscr();

a) Syntax error
b) No output/error
c) Stack  Overflow
d) Linker error
           




16.       main()
{
int i;
printf("%d",scanf("%d",&i));  // value 10 is given as input here
}
a) Error
b) 1
c) 2
d) 4


 


17.        main()
{
 show();
}
void show()
{
 printf("I'm the greatest");
}
a) prints I'm the greatest
b) Compiler error
c) Runtime error
d) prints 1







18.        main()
            {
            main();
            }
a) Syntax error
b) No output/error
c) Stack  Overflow
d) Linker error







19.        What are the following notations of defining functions known as?
i.      int abc(int a,float b)
                        {
                        /* some code */
 }
ii.    int abc(a,b)
        int a; float b;
                        {
                        /* some code*/
                        }





             
20.    What is printed when this program is executed
         main()
                {
                   printf ("%d\n",f(7)); 
                }
                  f(X)
                      {
                       
 if ( x<= 4)
                         return x;

                         return f(--x);
                      }
              a) 4
              b)5                                                                               
              c) 6
              d) 7
               



Answers : 
1 . b

2. Linker Error : Undefined symbol '_i'
extern storage class in the following declaration,
                                    extern int i;
specifies to the compiler that the memory for i is allocated in some other program and that address will be given to the current program at the time of linking. But linker finds that no other variable of name i is available in any other program with memory space allocated for it. Hence a linker error has occurred .

3. 0..1..2
 enum assigns numbers starting from 0, if not explicitly defined.

4. c

5. c 

6. three
The default case can be placed anywhere inside the loop. It is executed only when all other cases doesn't match. 

7. Compiler Error: Constant expression required in function main.
The case statement can have only constant expressions (this implies that we cannot use variable names directly so an error). Enumerated types can be used in case statements. 

8. Compiler Error: switch expression not integral
Switch statements can be applied only to integral types. 

9. d 

10. 011122

11. b

12. d

13. c

14. Some address will be printed.
Function names are just addresses (just like array names are addresses).
main() is also a function. So the address of function main will be printed. %p in printf specifies that the argument is an address. They are printed as hexadecimal numbers.

15.  No output/error 
The first clrscr() occurs inside a function. So it becomes a function call. In the second clrscr(); is a function declaration (because it is not inside any function).

16.  1
Scanf returns number of items successfully read and not 1/0.  Here 10 is given as input which should have been scanned successfully. So number of items read is 1.

17. Compier error: Type mismatch in redeclaration of show.
When the compiler sees the function show it doesn't know anything about it. So the default return type (ie, int) is assumed. But when compiler sees the actual definition of show mismatch occurs since it is declared as void. Hence the error.
The solutions are as follows:
1. declare void show() in main() .
2. define show() before main().
3. declare extern void show() before the use of show().

18.  Runtime error : Stack overflow.
main function calls itself again and again. Each time the function is called its return address is stored in the call stack. Since there is no condition to terminate the function call, the call stack overflows at runtime. So it terminates the program and results in an error.

19. i. ANSI C notation
ii. Kernighan & Ritche notation

20. a




Hope this is useful :)