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Sample Technical Questions

C Sample Question

146. main()
     {
     		int i = 257;
     	int *iPtr = &i;
     		printf("%d %d", *((char*)iPtr), *((char*)iPtr+1) );
     }

     Answer:

     1 1

     Explanation:

     The integer value 257 is stored in the memory as, 00000001 00000001, so the individual bytes are taken by casting it to char * and get printed.

147. main()
     {
     		int i = 258;
     	int *iPtr = &i;
     		printf("%d %d", *((char*)iPtr), *((char*)iPtr+1) );
     }

     Answer:

     2 1

     Explanation:

     The integer value 257 can be represented in binary as, 00000001 00000001. Remember that the INTEL machines are 'small-endian' machines. Small-endian means that the lower order bytes are stored in the higher memory addresses and the higher order bytes are stored in lower addresses. The integer value 258 is stored in memory as: 00000001 00000010.

148. main()
     {
     		int i=300;
     	char *ptr = &i;
     		*++ptr=2;
     	printf("%d",i);
     }

     Answer:

     556

     Explanation:

     The integer value 300 in binary notation is: 00000001 00101100. It is stored in memory (small-endian) as: 00101100 00000001. Result of the expression *++ptr = 2 makes the memory representation as: 00101100 00000010. So the integer corresponding to it is 00000010 00101100 => 556.

149. #include ‹stdio.h›
     main()
     {
     char * str = "hello";
     char * ptr = str;
     char least = 127;
     while (*ptr++)
                       least = (*ptr < least ) ?*ptr :least;
     printf("%d",least);
     }

     Answer:

     0

     Explanation:

     After 'ptr' reaches the end of the string the value pointed by 'str' is '\0'. So the value of 'str' is less than that of 'least'. So the value of 'least' finally is 0.

150. main()
     {
     struct student 
     {
     char name[30];
     struct date dob;
     }stud;
     struct date
             {	
              int day,month,year;
              };
          scanf("%s%d%d%d", stud.rollno, &student.dob.day, &student.dob.month,      &student.dob.year);
     }

     Answer:

     Compiler Error: Undefined structure date

     Explanation:

     Inside the struct definition of 'student' the member of type struct date is given. The compiler doesn't have the definition of date structure (forward reference is not allowed in C in this case) so it issues an error.

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