Re: [C_Programming] Quick Help:'C' questions from an Electronic company

Comment Below !!  (Where ever I felt it is neccessary to comment, 
leaving rest for you to try.)!!

Regards
Ranjeet

khem metre wrote:

> Hello friend ,
> following are the C questions asked in an electronic
> company.
> Please answer the questions with description:
>
> 1). What is the value of  X  after the execution  of
> follwing  program
>       on a machine that uses 16 bit integers?
>
>       int x=0x8000;
>       x>>=1;
>
> a) ox4000    b) 0xc000      c) 0x0   d) None of the above

    ans:  a) ox4000

>
>
> 2). On a perticular machine a C compiler implements 16
> bit integerts and 8 bit characters.
>      
>       int a[10];
>       char *b;
>       int *c, *d;
>
>       b=(char *) a;
>       c=a;
>       b=b+4;
>       d=(int *)b;
>       c++;
> what are data items to which b and c are pointing now?
>
> a) a[4] and a[1]
> b) a[2] and a[1]
> c) a[4] and a[2]
> d) a[5] and a[2]

    I dont find any of the option in my opinion:  the correct answer will be
    a[1], a[1]

>
>
> 3) Which is the correct output for follwing program:-
>         
>          unsigned int a=6;
>       int b= -20;
>       ( a + b > 6 ) ? puts(">6") : puts("<=6");
>
> a) >6
> b) <=6
> c) >6 and <=6
> d) none of the above

    Answer will be a) i.e

    over above you have the unsigned and the signed int
    now signed int  + ungined int  = unsigned int

    Let take the above case :

     unsigned int (6) + signed int(-20) = unsigned int (4294967282)
     Now which is definetly greater then 6 so condition satisfy.

    Now you must be amazed why we get the above value.

    6 + (-20) = -14

    Now as the compiler takes the above case: signed int  + ungined int 
 = unsigned int
     -14 is round of into its range : like below
     2 power 32 (Unsigned Int) =  (4294967296 - 14) = 4294967282

     No Doubt If The Compiler would have taken this as the documented thing:
    "signed int  + ungined int  = signed int" then your value will be -14
   
    anyway the motive behind this question to know weather you know
    this point :   signed int  + ungined int  = unsigned int  

  ASFAIK:   unsigned char + signed char           =  signed int]
                     unsigned char + signed short         = signed int
                     signed char + unsigned short         = signed int
                     unsigned char + signed int             = signed int
                     signed char + unsigned int             = unsigned int
                     unsigned short + signed int           = signed int
                     signed short + unsigned int          = unsigned int


  Please correct me others If I am worng.

>
>
>
> 4) A program needs to use a value of PI (i.e.  3.1400)
> in calculation.
> How would you declare value of PI using a macro?
> Note that highest possible resolution is desired.

     #define PI 22 / 7

> 5).  following C code uses a keyword  interrupt   to
> define an ISR .
> comment on the code.
>
>       interrupt double compute_area(radius)
>       double radius;
>       {
>             double area=PI * radius * radius;
>             return area;
>       }
>
>
> 6)  Each of the alphabets stand for one digit, in the
> following sum. Find the values for each of the
> alphabets. Indicate the logic used.
>      
>       F   O   R   T   Y
>      +          T   E   N
>      +          T   E   N
>       -----------------------
>         S   I   X   T   Y
>       -----------------------
>
> 7)  following are some valid instructions for a
> hypothetical microcontroller
> which result in loading the accumulator by 0.
> Which of these is most efficient?
> i.   mov a,0
> ii.  xor a,a
> iii. mul a,0
> iv.  sub a,a
>
> a) i
> b) ii
> c) iii
> d) iv
>
> 8) Two programs  develop 2 program modules a.c  and
> b.c  independently
> which are linked together.
>
> File- a.c contains following code:-
> static char a, b;
> main()
> {
>       fcall();
>       printf (" a=%d    b=%d  \n ", a , b);
> }
>
> File-    b.c    contains following code:-
> extern int a,b;
> void  fcall()
> {
>       a=10;
>       b=20;
> }
> Which of the following is the likely output of the
> program.
> a) a=10      b=0
> b) a=10      b=20
> c) a=0      b=20
> d) None as the linker would indicate an error
>
    answer:  d)

>
> 9) Which of the following expression evaluations would
> be most efficient?
> i. a=a*10;
> ii. a=a*8+a*2;
> iii. a=a<<3 + a<<1;
> iv. a=a<<3 + a+a;
>
> a) i
> b) ii
> c) iii
> d) iv

   Answer c) iii iii. a=a<<3 + a<<1;

>
>
> 10)       int a,b,c;
>       long d;
> Which of the following expressions evaluate the result
> with minimum
> loss of resolution.
> i.  d=a/b*c;
> ii. d=(long)a*c/b;
> iii. d=(a/b)*c;
> iv. d=(a*c)/b;
>
> a) ii
> b) iv
> c) ii and iv
> d) i

  answer    a) ii. d=(long)a*c/b;

>
>
> 11) Is the following piece of code incorrect ? If
> incorrect rectify the errors.
>
>       long percent (a,b)
>       long a,b;
>       {
>           long d;
>           d=(a*100)/b;
>           return d;
>       }
>
>       main()
>       {
>          int marksob , per, total;
>       total=1400;
>       scanf( " enter the marks obtained ", marksob);
> per=percent(marksob, total);
> printf("percentage is %3d.%2d \n",per/100, per%100);
> }

   

> 12) using vatiable a, give definations for following:-
> example :- 1) An integer  
>                     Answer:  int a;
> 2) A pointer to an integer
> 3) an array of 10 integers
> 4) An array of 10 pointers to integers
> 5) A pointer to an array of 10 integers
> 6) A pointer to a function that takes an integer as an
> argument and returns an integer
> 7) An array of ten pointers to functions that take an
> integer argument & return an integer.
>
> 13) write a  C function in a program  to decide
> whether the year is a leap year or not.
>        Note:-  optimize the function for execution
> time efficiency.
>
>
> 14)  A 100 Km long highway has 1 milestone after
> every Km.
>        Total how many milestones are there?
>
>
> 15) Convert following C program fragment into any of
> the assembly languages you know:
>       Note that a and b are character variables,
> and c is an integer variable.
>       if (a)
>              d++;
>       else
>                 if (c)
>             d - -;
>                             else
>             d=0;
>
>
>
>
>
>            
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