Exercises

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Exercises

1)What does the below print ? Explain your answer.
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File: exer1.cpp

#include <iostream>
using namespace std;

int main()
{

  int var1 = 32, *ptr = &var1 ;
  char ch = 'A', &cho = ch  ;
  cho += var1 ;
  *ptr += ch;
  cout << var1 << ", " << ch << endl;


  return 0;

}

2) What is the output of the following program ? Does it compile correctly ?

File: exer2.cpp

#include <iostream>
using namespace std;

int main()
{
    const int i1 = 20;
    const int* const ptr = &i1 ;
    (*ptr)++;
    int j1 = 15;
    ptr = &j1 ;
    cout << i1 ;

    return 0;
}

3) What is the output of the following program ?

File: exer3.cpp

#include <iostream>
using namespace std;

int main()
{
    int num[5];
    int* ptr ;
    ptr = num;
    *ptr = 10;
    ptr++;
    *ptr = 20;
    ptr = &num[2];
    *ptr = 30;
    ptr = num + 3;
    *ptr = 40;
    ptr = num;
    *(ptr + 4) = 50;
    for (int i1 = 0; i1 < 5; i1++)
      cout << num[i1] << ", ";
    return 0;
}

4) What is the output of the following program ?
File: exer4.cpp

#include <iostream>
using namespace std;

int main()
{
    int arr[] = { 4, 5, 6, 7 } ;
    int* ptr = (arr + 1) ;
    cout << *arr + 10;
    return 0;

}

5) What is the output of the following program ?
File: exer5.cpp

#include <iostream>
using namespace std;

int main()
{
    int a1 = 10, *pa, &ra ;
    pa = &a1 ;
    ra = a1 ;
    cout << "a1=" << ra ;

    return 0;
}

6) What is the difference between

 int  (*ptr)[5] ;

 and

 int *ptr[5]  ;

Show how the above are used by creating small sample programs .

7) What is the output of the following program ?
File: exer7.cpp

#include <stdio.h>
int main()
{
    int *ptr ;
    int x1 ;
    ptr = &x1 ;
    *ptr = 0 ;
    printf(" x1 = %d\n", x1) ;
    printf(" *ptr = %d\n", *ptr) ;
    *ptr += 5;
    printf(" x1  = %d\n", x1) ;
    printf(" *ptr = %d\n", *ptr) ;
    (*ptr)++ ;
    printf(" x1 = %d\n", x1) ;
    printf(" *ptr = %d\n", *ptr) ;
    return 0;

}

8) What is the output of the following program ?
File: exer8.cpp

#include <stdio.h>

int main()
{
    float arr[5] = {12.5, 10.0, 13.5, 90.5, 0.5};
    float *ptr1 = &arr[0];
    float *ptr2 = ptr1 + 3;
    printf("%f ", *ptr2);
    printf("%d", ptr2 - ptr1);
    return 0;

}

9) What is the output of the following program ?
File: exer8.cpp

#include<stdio.h>

int main()
{

int arr[] = {10, 20, 30, 40, 50, 60};
int *ptr1 = arr;
int *ptr2 = arr + 5;
printf("Number of elements between two pointer are: %d\n",
 (ptr2 - ptr1));
printf("Number of bytes between two pointers are: %d\n",
 (char*)ptr2 - (char*) ptr1);
return 0;

}

10) What is the output of the following program ?
File: exer10.cpp

#include <iostream>
using namespace std ;
int main()
{
    int x1[5] = { 1, 2, 3, 4, 5 };
    // ptr points to array x1
    int* ptr = x1;
    int i1;
    // exchange values usi1ng pointer
    for (i1 = 0; i1 < 2; i1++)
    {
        int temp = *(ptr + i1) ;
        *(ptr + i1) = *(ptr + 4 - i1) ;
        *(ptr + 4 - i1) = temp ;
    }
        // output the array x1
    for (i1 = 0; i1 < 5; i1++)
        cout << x1[i1] << " ";
    return 0;
}

11) What is the output of the following program ?
File: exer11.cpp

#include <iostream>
using namespace std ;
//-----------------------------------------------------------
int main()
{
    char c = 'T', d = 'S' ;
    char *p1 = &c ;
    char *p2 = &d ;
    char *p3 ;

    p3 = &d;
    cout << "*p3 = " << *p3 << endl ;
    p3 = p1;
    cout << "*p3 = " << *p3 << endl ;
    *p1 = *p2;
    cout << "*p1 = " << *p1  << endl ;

    return( 0 ) ;
}
//-----------------------------------------------------------

Solutions

6)
File: soln6.cpp

#include <iostream>
using namespace std;
int main()
{
    //Almost same as int* ptr but can only
    //point to a block of 5 integers
    int  (*ptr1)[5] ;

    //An array of 5 pointers
    int *ptr2[5]  ;
    int x1 = 100 ;
    int arr1[5]={ 1, 2, 3, 4, 5 } ;
    ptr1 = &arr1  ;
    ptr2[0] = &x1 ;
    return 0;
}