C Program Page 2

15:-
#include
main()
{
char s[]={'a','b','c','\n','c','\0'};
char *p,*str,*str1;
p=&s[3];
str=p;
str1=s;
printf("%d",++*p + ++*str1-32);
}
Answer:77
Explanation: p is pointing to character '\n'. str1 is pointing to character 'a' ++*p. "p is pointing to '\n' and that is incremented by one." the ASCII value of '\n' is 10, which is then incremented to 11. The value of ++*p is 11. ++*str1, str1 is pointing to 'a' that is incremented by 1 and it becomes 'b'. ASCII value of 'b' is 98. Now performing (11 + 98 – 32), we get 77("M"); So we get the output 77 :: "M" (Ascii is 77).

16:-
#include
main()
{
int a[2][2][2] = { {10,2,3,4}, {5,6,7,8} };
int *p,*q;
p=&a[2][2][2];
*q=***a;
printf("%d----%d",*p,*q);
}
Answer: SomeGarbageValue---1
Explanation: p=&a[2][2][2] you declare only two 2D arrays, but you are trying to access the third 2D(which you are not declared) it will print garbage values. *q=***a starting address of a is assigned integer pointer. Now q is pointing to starting address of a. If you print *q, it will print first element of 3D array.

17:-
#include
main()
{
struct xx
{
int x=3;
char name[]="hello";
};
struct xx *s;
printf("%d",s->x);
printf("%s",s->name);
}
Answer: Compiler Error
Explanation:You should not initialize variables in declaration

18:-
#include
main()
{
struct xx
{
int x;
struct yy
{
s;
struct xx *p;
};
struct yy *q;
};
}
Answer:Compiler Error
Explanation:The structure yy is nested within structure xx. Hence, the elements are of yy are to be accessed through the instance of structure xx, which needs an instance of yy to be known. If the instance is created after defining the structure the compiler will not know about the instance relative to xx. Hence for nested structure yy you have to declare member.

19:-
main()
{
printf("\nab");
printf("\bsi");
printf("\rha");
}
Answer: hai
Explanation: \n - newline
\b - backspace
\r - linefeed

20:-
main()
{
int i=5;
printf("%d%d%d%d%d%d",i++,i--,++i,--i,i);
}
Answer:45545
Explanation:The arguments in a function call are pushed into the stack from left to right. The evaluation is by popping out from the stack. and the evaluation is from right to left, hence the result.

21:-
#define square(x) x*x
main()
{
int i;
i = 64/square(4);
printf("%d",i);
}
Answer:64
Explanation:the macro call square(4) will substituted by 4*4 so the expression becomes i = 64/4*4 . Since / and * has equal priority the expression will be evaluated as (64/4)*4 i.e. 16*4 = 64

22:-
main()
{
char *p="hai friends",*p1;
p1=p;
while(*p!='\0')
++*p++;
printf("%s %s",p,p1);
}
Answer: ibj!gsjfoet
Explanation: ++*p++ will be parse in the given orderØ *p that is value at the location currently pointed by p will be takenØ ++*p the retrieved value will be incremented Ø when ; is encountered the location will be incremented that is p++ will be executedHence, in the while loop initial value pointed by p is ‘h’, which is changed to ‘i’ by executing ++*p and pointer moves to point, ‘a’ which is similarly changed to ‘b’ and so on. Similarly blank space is converted to ‘!’. Thus, we obtain value in p becomes “ibj!gsjfoet” and since p reaches ‘\0’ and p1 points to p thus p1doesnot print anything.

23:-
#include
#define a 10
main()
{
#define a 50
printf("%d",a);
}
Answer:50
Explanation:The preprocessor directives can be redefined anywhere in the program. So the most recently assigned value will be taken.

24:-
#define clrscr() 100
main()
{
clrscr();
printf("%d\n",clrscr());
}
Answer:100
Explanation:Preprocessor executes as a seperate pass before the execution of the compiler. So textual replacement of clrscr() to 100 occurs.The input program to compiler looks like this : main()
{
100;
printf("%d\n",100);
}
Note: 100; is an executable statement but with no action. So it doesn't give any problem

25:-
main()
{
printf("%p",main);
}
Answer: Some address will be printed.
Explanation: 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.

26:-
main()
{
clrscr();
}
clrscr();
Answer:No output/error
Explanation: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).

27:-
enum colors {BLACK,BLUE,GREEN}
main()
{
printf("%d..%d..%d",BLACK,BLUE,GREEN);
return(1);
}
Answer: 0..1..2
Explanation: enum assigns numbers starting from 0, if not explicitly defined.

28:-
void main()
{
char far *farther,*farthest;
printf("%d..%d",sizeof(farther),sizeof(farthest));
}
Answer: 4..2
Explanation: the second pointer is of char type and not a far pointer

29:-
main()
{
int i=400,j=300;
printf("%d..%d");
}
Answer: 400..300
Explanation: printf takes the values of the first two assignments of the program. Any number of printf's may be given. All of them take only the first two values. If more number of assignments given in the program, then printf will take garbage values.

30:-
main()
{
char *p;
p="Hello";
printf("%c\n",*&*p);
}
Answer: H
Explanation: * is a dereference operator & is a reference operator. They can be applied any number of times provided it is meaningful. Here p points to the first character in the string "Hello". *p dereferences it and so its value is H. Again & references it to an address and * dereferences it to the value H.