Test your C Programming skills Part 4

Q1. How scanf will execute?
main(){

   char name[10],s[12];
   scanf(" \"%[^\"]\"",s);

}

Ans:

First it checks for the leading white space and discards it.Then it matches
with a quotation mark and then it reads all character upto another quotation mark.

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Q2. What will be the position of the file marker?

a) fseek(ptr,0,SEEK_SET);

b) fseek(ptr,0,SEEK_CUR);

Ans:

a) The SEEK_SET sets the file position marker to the starting of the file.
b) The SEEK_CUR sets the file position marker to the current position of the file.

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Q3. What is the problem with the following code segment?

while ((fgets(receiving array,50,file_ptr)) != EOF)

Ans:

fgets returns a pointer. So the correct end of file check is checking for !=

NULL.

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Q4. Find the o/p:
main(){

   char *cptr,c;
   void *vptr,v;

   c=10; v=0;
   cptr=&c; vptr=&v;

   printf("%c%v",c,v);

}

Ans:

Compiler error (at line number 4): size of v is Unknown.

Explanation:
You can create a variable of type void * but not of type void, since void is
an empty type. In the second line you are creating variable vptr of type void * and
v of type void hence an error.

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Q5. Find the o/p:
#define max 5

#define int arr1[max]

main(){

   typedef char arr2[max];
   arr1 list={0,1,2,3,4};

   arr2 name="name";

   printf("%d %s",list[0],name);

}
Ans:

Compiler error (in the line arr1 list = {0,1,2,3,4})

Explanation:
arr2 is declared of type array of size 5 of characters. So it can be used to
declare the variable name of the type arr2. But it is not the case of arr1. Hence an

Rule of Thumb:
#defines are used for textual replacement whereas typedefs are used for
declaring new types.

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Q6. Find the o/p:
int i=10;

main() {

   extern int i; {

   int i=20;{
     int i=30;
     printf("%d",i);

   }

   printf("%d",i);

   }

   printf("%d",i);

}
Ans:

30,20,10

Explanation:
'{' introduces new block and thus new scope. In the innermost block i is
declared as, const volatile unsigned which is a valid declaration. i is assumed of
type int. So printf prints 30. In the next block, i has value 20 and so printf prints
20. In the outermost block, i is declared as extern, so no storage space is allocated
for it. After compilation is over the linker resolves it to global variable i (since it
is the only variable visible there). So it prints i's value as 10.

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Q7. Find the o/p:
main(){

   int *j;{
     int i=10;
     j=&i;
   }

   printf("%d",*j);

}

Ans:

     10

Explanation:
The variable i is a block level variable and the visibility is inside that
block only. But the lifetime of i is lifetime of the function so it lives upto the exit
of main function. Since the i is still allocated space, *j prints the value stored in i
since j points i.

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Q8. Find the o/p:
# include < stdio.h >
main() {

const int i=4;

float j;

   j = ++i;

   printf("%d %f", i,++j);

}
Ans:

Compiler error

Explanation:
i is a constant. you cannot change the value of constant

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Q9. Find the o/p:
main() {

int i=_l_abc(10);

   printf("%d\n",--i);

}

int _l_abc(int i) {

return(i++);

}

Ans:

     9

Explanation:
return(i++) it will first return i and then increments. i.e. 10 will be
returned.

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Q10. Find the o/p of this:
main(int argc, char **argv) {

   printf("enter the character");
   getchar();

   sum(argv[1],argv[2]);

}

sum(num1,num2)int num1,num2; {

return num1+num2;

}
Ans:

Explanation:
argv[1] & argv[2] are strings. They are passed to the function sum without
converting it to integer values.

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Q11. Find the o/p:
int one_d[]={1,2,3};

main(){

int *ptr;

   ptr=one_d;
   ptr+=3;

   printf("%d",*ptr);
}

Ans:

garbage value

Explanation:
ptr pointer is pointing to out of the array range of one_d.

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Q12. Find the o/p:
main(){

FILE *ptr;
char i;

   ptr=fopen("zzz.c","r");
   while((i=fgetch(ptr))!=EOF)
      printf("%c",i);

}

Ans:

contents of zzz.c followed by an infinite loop

Explanation:
The condition is checked against EOF, it should be checked against
NULL.

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Q13.Find the o/p:
int i;

main(){

int t;

   for ( t=4;scanf("%d",&i)-t;printf("%d\n",i))
      printf("%d--",t--);

}

// If the inputs are 0,1,2,3 find the o/p

Ans:

4--0

3--1

2--2

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