CHAPTER-7
POINTERS
1.Can you combine the following two statements into one
char *p;
p=malloc(100);
Ans: char *p=malloc(100);
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2.Can you split the following statement into two statements?
Char far *scr=(char far*) 0xb8000000L;
Ans:
Char far *scr;
Scr=(char far*) 0xb8000000L;
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3.Are the expressions *ptr++ and ++*ptr same?
Ans: No. *ptr++ increments the pointer and not the value pointed by it, whereas ++*ptr increments the value being pointed to by ptr.
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4. Can You write another expression which does the same job as ++*ptr?
Ans: (*ptr)++
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5.What would be the equivalent pointer expression for referring the same element as a[i][j][k][l]?
Ans: *(*(*(*(a+i)+j)+k)+l)
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6.O/p?
main()
{
int arr[]=(12,13,14,15,16};
printf(“\n%d %d %d”,sizeof(arr),sizeof(*arr),sizeof(arr[0]));
}
Ans: 10 2 2
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7.What would be the O/P of the program assuming that the array begins at 1002?
Main()
{
int a[3][4]={
1,2,3,4,
5,6,7,8,
9,10,11,12
};
printf(“\n%u %u %u”,a[0]+1,*(a[0]+1),*(*(a+0)+1));
}
Ans: 1004 2 2
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8.What would be the output of the program assuming that the array begins at location 1002?
Main()
{
int a[2][3][4]={
{
1,2,3,4,
5,6,7,8,
9,1,1,2
},
{
2,1,4,7,
6,7,8,9,
0,0,0,0
}
}
printf(“\n %u %u %u %d”,a,*a,**a,***a);
Ans:1002 1002 1002 1
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9.In the following program how would you print 50 using p?
main()
{
int a[]={10,20,30,40,50}
char *p;
p=(char*)a;
}
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10.Where can one think of using pointers?
Ans: At lot of places,for eg
Accessing array or string elements
Dynamic memory allocation
Call by referance
Implementing linked lists, trees, graphs, and many other data structures
Etc.
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11.In the following program add a statement in the function fun() such that the address of a gets stored in j.
main()
{
int *j;
void fun(int**);
fun(&j);
}
void fun(int**k)
{
int a=10;
/* add statement here*/
}
Ans: *k=&a;
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12.How would you implement an array of three function pointers where each function receives two ints and return a float?
Ans: float (*arr[3])(int,int);
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13. Would the following program give a compilation error or warning?
main()
{
float i=10,*j;
void *k;
k=&i;
j=k;
printf(“\n%f”,*j);
}
Ans: No. Hee no type casting is required while assigning the value to and from k because conversions are applied automatically when other pointer types are assigned to and from void*.
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14. Would the following program compile?
main()
{
int a=10,*j;
void *k;
j=k=&a;
j++;
k++;
printf(“\n %u %u”,j,k);
}
Ans: No. An error would be reported in the statement k++ since arithmetic on void pointers is not permitted unless the void pointer is appropriately typecasted.
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15. Would the following code compile successfully?
main()
{
printf(“%c”,7[“Sundaram”]);
}
Ans: YES. Prints m of sundaram.
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