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Sample Technical Questions

C Sample Question

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.

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