Question { 18798 }

How does free() know how many bytes to free?

Answer

Heap memory menager is a person, who is responsible for
dynamic memory allocation. He will maintains a internal
data structure(table) to update the information on free and
allocated memory pools. when memory is allocated using
malloc or calloc, the heap memory manager will update the
table(which tells, no of bytes allocated to a particular
pointer) and returns the base address to the application.
when application calls free() with the pointer to be freed
as a argument, free will look into the table which holds no
of bytes allocated for that pointer. And it will free those
many bytes from the base address. Again the freed memory
shall be added to a free memory pool so that other fellows
who needs memory can utilise it.

Question { HCL, 24921 }

main()
{
char *p1="Name";
char *p2;
p2=(char *)malloc(20);
while(*p2++=*p1++);
printf("%s\n",p2);
}
what is the output?

Answer

In addtion to the answer #5.

printf("%s\n",p2); will print the values from 6th byte to
20th byte.

6th byte to 20th bytes of the memory will contain some
Garbage value. So the output will be a string of garbage
values.


For desired o/p see the ans #5

Question { HCL, 24921 }

main()
{
char *p1="Name";
char *p2;
p2=(char *)malloc(20);
while(*p2++=*p1++);
printf("%s\n",p2);
}
what is the output?

Answer

Hi all,

#1 Mannucse's ans is wrong. cos as mentioned "Name" will
not be the output.

#2 Sanath's ans is wrong. Cos at the end of the while loop,
p2 will not point to NULL. It will point to the next byte
to the NULL termination ie., 6th byte.

#3 Shruti's ans is wrong. cos i think she got confused
between assignment(=) and comparisonal(==) operators. And
the statement given as "we cannot copy the value of p1 in
p2, the way its mentioned here" is absolutely wrong.


So,
Lets Analyse the program and how to get the required output.

hav a look on th program again.

main()
{
char *p1="Name";
char *p2;
p2=(char *)malloc(20);
while(*p2++ = *p1++)
{
printf("TEST \n");
}
printf("%s\n",p2);
getch();
}

Here, in every iteration of while loop, we are assigning
*p1 to *p2, and incrementing both pointers p1 and p2, After
completion(when *p1 value would be '\0')of the while loop,
first 5 bytes of p2 holds the
characters 'N','a','m','e' '\0'. At the end of while loop
p2 points to the 6th byte in the memory.

So, now printf("%s\n",p2); shall start print the values
from the 6th byte to 20th bytes of the memory which was
allocated dynamically.
----------------------------------
To get the desired output change the printf statement to
printf("%s\n",p2-5);

Now (p2-5) points to the starting address of p2 and will
print the values in the memory till it encounters '\0'
termination. ie., The output would be -> Name

Question { 4044 }

Write a program that accepts a string where multiple spaces
are given in between the words. Print the string ignoring
the multiple spaces.

Example:

Input: “ We Are Student “
Output: "We Are Student"

Answer

#include
main()
{
char *p, *q, *q1;
p = (char *)malloc(200);
q = (char *)malloc(200);
q1 = q;
printf("ENTER THE SENTENCE: \n");
p = gets(p);
while(*p != '\0')
{
if(*p != ' ' || *(q -1) != ' ')
{
*q++ = *p++;
}
else
p++;
}
*q = '\0';
printf("%s", q1);
getch();
}

Is This Answer Correct ?

0 Yes

0 No

Question { IBM, 10297 }

Write a program that accepts a string where multiple spaces
are given in between the words. Print the string ignoring
the multiple spaces.

Example:
Input: “ We.....Are....Student “ Note: one .=1 Space
Output: "We Are Student"

Answer

Hi all,

Its enough to have this much length of code below. And I
feel no need to have any temp variables(but i used one temp
pointer).

#include
main()
{
char *p, *q, *q1;
p = (char *)malloc(100);
q = (char *)malloc(100);
q1 = q;
printf("ENTER THE SENTENCE WITH MULTIPLE SPACES: \n");
gets(p);
while(*p != '\0')
{
if(*p != ' ' || *(q -1) != ' ')
{
*q++ = *p++;
}
else
p++;
}
*q = '\0';
printf("%s", q1);
getch();
}

Is This Answer Correct ?

0 Yes

1 No

Question { 7703 }

write the function int countchtr(char string[],int
ch);which returns the number of timesthe character ch
appears in the string. for example the call countchtr("she
lives in Newyork",'e') would return 3.

Answer

#include
#include

int main()
{
char ptr[100]= "She lives in NEWYORK";
char ch;
printf("ENTER THE CHARACTER:\n");
scanf("%c", &ch);
printf("CHAR %c EXIST %d TIME(S)\n",ch, countchtr(ptr, ch));
getch();
}

int countchtr(char *ptr, char ch)
{
int count = 0;
char ch1;
if(ch >= 97 && ch <= 122)
{
ch1 = ch - 32;
}
else if(ch >= 65 && ch <= 96)
{
ch1 = ch + 32;
}
while(*ptr != '\0')
{ if((*ptr == ch) || (*ptr == ch1))
{
count++;
}
ptr++;
}
return count;
}

Is This Answer Correct ?

1 Yes

0 No

Question { 5790 }

plz answer.. a program that takes a string e.g. "345" and
returns integer 345

Answer

The equalent code to atoi() library fuction which i hav
written, below.


#include
#include

int MyAtoi(char *cptr);

main()
{
char *cptr = "123445";

printf("INTEGER EQU IS: %d\n", MyAtoi(cptr));
getch();
}
int MyAtoi(char *cptr)
{
int iptr = 0;
while((*cptr != '\0') && ((*cptr >= 48 && *cptr <= 57) ||
(*cptr == 32)))
{
if(*cptr != ' ')
iptr = (iptr * 10) + (*cptr - 48);
cptr++;
}
return iptr;
}

Is This Answer Correct ?

0 Yes

0 No

Question { Verifone, 14087 }

struct ptr
{
int a;
char b;
int *p;
}abc;
what is d sizeof structure without using "sizeof" operator??

Answer

Hi All,
The size of any data type is depends on the compiler
(including struct, union and enum). But the question does
not mean, "what is the size of the given structure".

It actually means,
Find the size of the structure without using sizeof()
operator.

The Answer, irrespective of compiler would be,

Output of the following code.

-First printf gives the size of the structure, wthout using
size of operator.

-U can cross check the ans using sizeof() operator in the
second printf().

#include
struct name
{
int a;
char b;
int *p;
}abc;

main()
{
struct name *ptr, *ptr1;
ptr = &abc;
ptr1 = ptr + 1;
printf("WITHOUT USING sizeof() OPERATOR: %d \n",((char *)
ptr1 - (char *)ptr));
printf("USING sizeof() OPERATOR: %d \n", sizeof(abc));
getch();
}

Is This Answer Correct ?

13 Yes

0 No

Question { Adobe, 5719 }

What are bit fields? What is their use?

Answer

Bit fields main intention is to reduce the memory
consumption.

Syntax:
------

struct
{
int a:1;
/*whatever may be the size of the int(compiler dependent),
only one bit shall be allocated for variable 'a'*/
}BITFIELDS;

Restictions:
------------
1. Accessing or printing address of bitfield variable is
not possible.
2.Array of bit fields, not possible.
3.A function cannot return a bit field variable.

Question { Adobe, 25292 }

Write code for atoi(x) where x is hexadecimal string.

Answer

Hi,
Refer below link to know how atoi() lib fuction works.
http://www.cppreference.com/wiki/c/string/atoi

And find the equalent code which i have written here.

#include
#include

int MyAtoi(char *cptr);

main()
{
/*Give different inputs like "12.3432", "a4523"," 123"
"abcd", "1234f" and find the qualent output*/

char *cptr = "123445";

printf("INTEGER EQU IS: %d\n", MyAtoi(cptr));
getch();
}
int MyAtoi(char *cptr)
{
int iptr = 0;
while((*cptr != '\0') && ((*cptr >= 48 && *cptr <= 57) ||
(*cptr == 32)))
{
if(*cptr != ' ')
iptr = (iptr * 10) + (*cptr - 48);
cptr++;
}
return iptr;
}

Is This Answer Correct ?

3 Yes

0 No

Question { Adobe, 8265 }

Two's compliment of -5

Answer

2's compliment of a -ve no is, positive value of the same
no.

#include
#include
void main()
{
int no1, res;
printf("ENTER THE NEGATIVE NO: \n");
scanf("%d", &no1);
no1 = ~(no1);
res = no1 | 0x01;
printf("\nRESULT: %d", res);
getch();
}

Is This Answer Correct ?

0 Yes

5 No

Question { Adobe, 10714 }

CopyBits(x,p,n,y)
copy n LSBs from y to x starting LSB at 'p'th position.

Answer

Hi,
The below code ll giv desired o/p.

#include
#include

int main()
{
int x, y, n , p, i, j, temp;
printf("ENTER X, Y, NO OF BITS AND BIT POSITION: \n");
scanf("%d %d %d %d",&x, &y, &n, &p);
for(i = p, j = 0; i < n+p; i++, j++)
{
if(x & (0x01 << i))
x = x^(0x01< temp = y & (0x01< x = x | (temp << i-1);
}
printf("VALUE OF X:%d \n",x);
getch();
}

Is This Answer Correct ?

0 Yes

0 No

Question { Adobe, 10714 }

CopyBits(x,p,n,y)
copy n LSBs from y to x starting LSB at 'p'th position.

Answer

Hi,
Small bug is there in the above code, which i have posted.
But the same has been resolved here.

#include
#include

int main()
{
int x, y, n , p, i, j, temp;
printf("ENTER X, Y, NO OF BITS AND BIT POSITION: \n");
scanf("%d %d %d %d",&x, &y, &n, &p);
for(i = p, j = 0; i < n+p; i++, j++)
{
if(x & (0x01 << i-1))
x = x^(0x01 << i-1);
temp = y & (0x01 << j) ? 1 : 0;
x = x | (temp << i-1);
}
printf("VALUE OF X:%d \n",x);
getch();
}

Is This Answer Correct ?

0 Yes

0 No

Question { Wipro, 20608 }

Difference between null pointer and dangling pointer?

Answer

To Sourisengupta Question.

free() shall free the memory which is allocated dynamically.

But afrer the free() function being called,the pointer
which u r passing to free() as an argument, shall point to
the same base address, which is no more valid.

Question { Wipro, 20608 }

Difference between null pointer and dangling pointer?

Answer

Minor correction in my ans #4...

To Sourisengupta Question.

free() shall free the memory which is allocated dynamically.

But afrer the free() function being called,the pointer
which u r passing to free() as an argument, shall point to
the same base address, which is no more valid(ie., address
is valid but no more in the allocated memory pool. It will
be added in the free memory pool).