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7.9 Exercises

With the following declaration:

int *p, x[10];
    char *t, s[100];

1. 1. x

   2. x + i

   3. *(x + i)

   4. x++;

2. 1. p = x;

   2. *p

   3. p++;

   4. p++;

   5. p--;

   6. --p;

3. 1. p = x + 5;

   2. *p;

   3. --p;

   4. p*;

4. scanf("%s", s);

   Input: Hello, Hello.

5. printf("%s\n", s);

6. scanf("%s", t);
       t = s;
       scanf("%s", t);

   Check the following problems; find and correct errors, if any. What will be the output in each case.

7. main()
   {   int i, x[10] = { 1, 2, 3, 4};
   
       for (i = 0; i < 10; i++) {
            printf("%d\n", *x);
            x++;
       }
   }

8. main()
   {   int i, *ptr, x[10] = { 1, 2, 3, 4};
   
       for (i = 0; i < 10; i++) {
            printf("%d\n", *ptr);
            ptr++;
       }
   }

9. main()
   {   int i, x[10] = { 1, 2, 3, 4};
   
       for (i = 0; i < 10; i++)
            printf("%d\n", (x + i));
   }

10. main()
    {   int i, x[10] = { 1, 2, 3, 4};
    
        for (i = 0; i < 10; i++)
             printf("%d\n", *(x + i));
    }

11. main()
    {   int i, *ptr, x[10] = {1, 2, 3, 4};
    
        ptr = x;
        for (i = 0; i < 10; i++) {
             printf("%d\n", *ptr);
             ptr++;
        }
    }

12. main()
    {   int i, *ptr, x[10] = {1, 2, 3, 4};
    
        ptr = x;
        for (i = 0; i < 10; i++) {
             printf("%d\n", ptr);
             ptr++;
        }
    }

13. main()
    {   char x[10];
    
        x = "Hawaii;
        printf("%s\n", x);
    }

14. main()
    {   char *ptr;
    
        ptr = "Hawaii";
        printf("%s\n", ptr);
    }

15. main()
    {   char *ptr, x[10] = "Hawaii";
    
        for (i = 0; i < 10; i++)
             printf("%d %d %d\n", x + i, *(x + i), x[i]);
    }

16. main()
    {   char x[10];
    
        scanf("%s", x);
        printf("%s\n", x);
    }

    The Input is:

    Good Day to You

17. main()
    {   char *ptr;
    
        scanf("%s", ptr);
        printf("%s\n", ptr);
    }

    The Input is:

    Good Day to You

18. Here is the data stored in an array

    char s[100];
    
        Hawaii\0Manoa\0

    What will be printed out by the following loop?

    i = 0;
        while (s[i]) {
             putchar(s[i]);
             i++;
        }