MCQ

1. The C language terminator is
(a) semicolon (b) colon (c) period (d) exclamation mark

2. What is false about the following -- A compound statement is
(a) A set of simple statements (b) Demarcated on either side by curly brackets
(c) Can be used in place of simple statement (d) A C function is not a compound statement.

3. What is true about the following C Functions
(a) Need not return any value (b) Should always return an integer
(c) Should always return a float (d) Should always return more than one value

4. Main must be written as
(a) The first function in the program (b) Second function in the program
(c) Last function in the program (d) Any where in the program

5. Which of the following about automatic variables within a function is correct ?
(a) Its type must be declared before using the variable (b) They are local
(c) They are not initialized to zero (d) They are global

6. Write one statement equivalent to the following two statements: x=sqr(a); return(x);
Choose from one of the alternatives
(a) return(sqr(a)); (b) printf("sqr(a)");
(c) return(a*a*a); (d) printf("%d",sqr(a));

7. Which of the following about the C comments is incorrect ?
(a) Comments can go over multiple lines
(b) Comments can start any where in the line
(c) A line can contain comments with out any language statements
(d) Comments can occur within comments

8. What is the value of y in the following code?
x=7;
y=0;
if(x=6) y=7;
else y=1;
(a) 7 (b) 0 (c) 1 (d) 6

9. Read the function conv() given below
conv(int t)
{
int u;
u=5/9 * (t-32);
return(u);
}
What is returned
(a) 15 (b) 0 (c) 16.1 (d) 29

10. Which of the following represents true statement either x is in the range of 10 and 50 or y is zero
(a) x >=10 && x <= 50 || y = = 0 (b) x<50 style="mso-spacerun:yes"> x >= 50 (d) None of these

11. Which of the following is not an infinite loop ?
(a) while(1)\{ ....} (b) for(;;){...}
(c) x=0; (d) # define TRUE 0
do{ /*x unaltered within the loop*/ ...
.....}while(x = = 0); while(TRUE){ ....}

12. What does the following function print?
func(int i)
{
if(i%2)return 0;
else return 1;
}
main()
{
int =3;
i=func(i);
i=func(i);
printf("%d",i);
}
(a) 3 (b) 1 (c) 0 (d) 2

13. How does the C compiler interpret the following two statements
p=p+x;
q=q+y;
(a) p= p+x; (b)p=p+xq=q+y; (c)p= p+xq; (d)p=p+x/q=q+y;
q=q+y; q=q+y;

RECURSIVE

1. GCD

int gcd(int,int);

int main()

{

int x,y;

printf("\nENTER TWO NO.S");

scanf("%d %d ",&x,&y);

printf("THE GCD OF TWO NO.IS %d", gcd(x,y));

getch();

}

int gcd(intx,inty)

{

if(y==0)

return(x);

else

return gcd(y,x%y);

}

some C problem

Note : All the programs are tested under Turbo C/C++ compilers.

It is assumed that,

Ø Programs run under DOS environment,

Ø The underlying machine is an x86 system,

Ø Program is compiled using Turbo C/C++ compiler.

The program output may depend on the information based on this assumptions (for example sizeof(int) == 2 may be assumed).

Predict the output or error(s) for the following:

1. void main()

{

int const * p=5;

printf("%d",++(*p));

}

Answer:

Compiler error: Cannot modify a constant value.

Explanation:

p is a pointer to a "constant integer". But we tried to change the value of the "constant integer".

2. main()

{

char s[ ]="man";

int i;

for(i=0;s[ i ];i++)

printf("\n%c%c%c%c",s[ i ],*(s+i),*(i+s),i[s]);

}

Answer:

mmmm

aaaa

nnnn

Explanation:

s[i], *(i+s), *(s+i), i[s] are all different ways of expressing the same idea. Generally array name is the base address for that array. Here s is the base address. i is the index number/displacement from the base address. So, indirecting it with * is same as s[i]. i[s] may be surprising. But in the case of C it is same as s[i].

3. main()

{

float me = 1.1;

double you = 1.1;

if(me==you)

printf("I love U");

else

printf("I hate U");

}

Answer:

I hate U

Explanation:

For floating point numbers (float, double, long double) the values cannot be predicted exactly. Depending on the number of bytes, the precession with of the value represented varies. Float takes 4 bytes and long double takes 10 bytes. So float stores 0.9 with less precision than long double.

Rule of Thumb:

Never compare or at-least be cautious when using floating point numbers with relational operators (== , >, <, <=, >=,!= ) .

4. main()

{

static int var = 5;

printf("%d ",var--);

if(var)

main();

}

Answer:

5 4 3 2 1

Explanation:

When static storage class is given, it is initialized once. The change in the value of a static variable is retained even between the function calls. Main is also treated like any other ordinary function, which can be called recursively.

5. main()

{

int c[ ]={2.8,3.4,4,6.7,5};

int j,*p=c,*q=c;

for(j=0;j<5;j++)>

printf(" %d ",*c);

++q; }

for(j=0;j<5;j++){

printf(" %d ",*p);

++p; }

}

Answer:

2 2 2 2 2 2 3 4 6 5

Explanation:

Initially pointer c is assigned to both p and q. In the first loop, since only q is incremented and not c , the value 2 will be printed 5 times. In second loop p itself is incremented. So the values 2 3 4 6 5 will be printed.

6. main()

{

extern int i;

i=20;

printf("%d",i);

}

Answer:

Linker Error : Undefined symbol '_i'

Explanation:

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 .

7. main()

{

int i=-1,j=-1,k=0,l=2,m;

m=i++&&j++&&k++||l++;

printf("%d %d %d %d %d",i,j,k,l,m);

}

Answer:

0 0 1 3 1

Explanation :

Logical operations always give a result of 1 or 0 . And also the logical AND (&&) operator has higher priority over the logical OR (||) operator. So the expression ‘i++ && j++ && k++’ is executed first. The result of this expression is 0 (-1 && -1 && 0 = 0). Now the expression is 0 || 2 which evaluates to 1 (because OR operator always gives 1 except for ‘0 || 0’ combination- for which it gives 0). So the value of m is 1. The values of other variables are also incremented by 1.

8. main()

{

char *p;

printf("%d %d ",sizeof(*p),sizeof(p));

}

Answer:

1 2

Explanation:

The sizeof() operator gives the number of bytes taken by its operand. P is a character pointer, which needs one byte for storing its value (a character). Hence sizeof(*p) gives a value of 1. Since it needs two bytes to store the address of the character pointer sizeof(p) gives 2.

9. main()

{

int i=3;

switch(i)

{

default:printf("zero");

case 1: printf("one");

break;

case 2:printf("two");

break;

case 3: printf("three");

break;

}

}

Answer :

three

Explanation :

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

10. main()

{

printf("%x",-1<<4);

}

Answer:

fff0

Explanation :

-1 is internally represented as all 1's. When left shifted four times the least significant 4 bits are filled with 0's.The %x format specifier specifies that the integer value be printed as a hexadecimal value

CPU

cache memory

Figure shows three levels of cache and introduces the nomenclature we will use in the remainder of the document. L1d is the level 1 data cache, L1i the level 1 instruction cache, etc. Note that this is a schematic; the data flow in reality need not pass through any of the higher-level caches on the way from the core to the main memory. CPU designers have a lot of freedom designing the interfaces of the caches. For programmers these design choices are invisible.

In addition we have processors which have multiple cores and each core can have multiple “threads”. The difference between a core and a thread is that separate cores have separate copies of (almost {Early multi-core processors even had separate 2^nd level caches and no 3^rd level cache.}) all the hardware resources. The cores can run completely independently unless they are using the same resources—e.g., the connections to the outside—at the same time. Threads, on the other hand, share almost all of the processor's resources. Intel's implementation of threads has only separate registers for the threads and even that is limited, some registers are shared.

operating system

The most important program that runs on a computer. Every general-purpose computer must have an operating system to run other programs. Operating systems perform basic tasks, such as recognizing input from thekeyboard, sendingoutput to the display screen, keeping track offiles and directories on thedisk, and controllingperiperal devices such as disk drives and printers. For large systems, the operating system has even greater responsibilities and powers. It is like a traffic cop -- it makes sure that different programs and user running at the same time do not interfere with each other. The operating system is also responsible for security, ensuring that unauthorized users do not access the system. Operating systems can be classified as follows: multi-user: Allows two or more users to run programs at the same time. Some operating systems permit hundreds or even thousands of concurrent users. multiprocessing: Supportsrunning a program on more than one CPU multitasking: Allows more than one program to run concurrently. multithreading: Allows different parts of a single program to run concurrently. real time: Responds to input instantly. General-purpose operating systems, such asDOS andUNIX, are not real-time. Operating systems provide a software platformon top of which other programs, called applicationprograms,can run. The application programs must be written to run on top of a particular operating system. Your choice of operating system, therefore, determines to a great extent the applications you can run. For PCs, the most popular operating systems are DOS, OS/2, and Windows, but others are available, such as Linux. As a user, you normally interact with the operating system through a set of commands. For example, the DOS operating system contains commands such as COPY and RENAME for copying files and changing the namesof files, respectively. The commands are accepted and executed by a part of the operating system called thecommand processor or command line interpreter. graphical user interfaceallow you to enter commands by pointing and clicking at objectsthat appear on the screen.