Output of C++ programs | Set 50

Predict the output of the following C++ programs:

Question 1: 
 

#include <cstdlib>
#include <iostream>
using namespace std;
int main()
{
    int ran = rand();
    cout << ran << endl;
    return 0;
}

1804289383

Explanation: As the declared number is an integer, It will produce the random number from 0 to RAND_MAX. The value of RAND_MAX is library-dependent but is guaranteed to be at least 32767 on any standard library implementation.

Question 2:

#include <cstdlib>
#include <iostream>
using namespace std;

int main()
{
    cout << RAND_MAX << endl;
    return 0;
}

2147483647

Explanation: The output is Compiler Dependent. RAND_MAX is a function used by the compiler to create a maximum random number.

Question 3:

#include <iostream>
using namespace std;
int main()
{
    void a = 10, b = 10;
    int c;
    c = a + b;
    cout << c;
    return 0;
}

Output

Compile time error

Explanation: void will not accept any values to its type. 

Question 4:

#include <iostream>

using namespace std;

int array1[] = { 1200, 200, 2300, 1230, 1543 };
int array2[] = { 12, 14, 16, 18, 20 };
int temp, result = 0;
int main()
{
    for (temp = 0; temp < 5; temp++) {
        result += array1[temp];
    }
    for (temp = 0; temp < 5; temp++) {
        result += array2[temp];
    }
    cout << result;
    return 0;
}

6553

Explanation: In this program we are adding the every element of two arrays. All the elements of array1[] and array2[] will be added and the sum will be stored in result and hence output is 6553.

Question 5:

#include <iostream>
using namespace std;
int main()
{
    int a = 5, b = 10, c = 15;
    int arr[3] = { &a, &b, &c };
    cout << *arr[*arr[1] - 8];
    return 0;
}

Output

Compile time error!

Explanation: The conversion is invalid in this array. The array arr[] is declared to hold integer type value but we are trying to assign references(addresses) to the array so it will arise error. The following compilation error will be raised: 

cannot convert from ‘int *’ to ‘int’

Question 6:

#include <iostream>
using namespace std;
int main()
{
    int array[] = { 10, 20, 30 };
    cout << -2 [array];
    return 0;
}

-30

Explanation: -2[array]: this statement is equivalent to -(array[2]). At the zero index 30 is stored hence negation of 30 will be printed due to unary operator (-).

Question 7:

#include <iostream>
using namespace std;
int main()
{
    int const p = 5;
    cout << ++p;
    return 0;
}

Output

Compile time Error!

Explanation: Constant variables are those whose value can't be changed throughout the execution. ++p statement try to change the value hence compiler will raise an error.

Question 8:
 

#include <iostream>
using namespace std;
int main()
{
    char arr[20];
    int i;
    for (i = 0; i < 10; i++)
        *(arr + i) = 65 + i;
    *(arr + i) = '\0';
    cout << arr;
    return (0);
}

ABCDEFGHIJ

Explanation: Each time we are assigning 65 + i. In first iteration i = 0 and 65 is assigned. So it will print from A to J. 

Question 9: 

#include <iostream>
using namespace std;
int Add(int X, int Y, int Z)
{
    return X + Y;
}
double Add(double X, double Y, double Z)
{
    return X + Y;
}
int main()
{
    cout << Add(5, 6);
    cout << Add(5.5, 6.6);
    return 0;
}

Output

Compile time error!

Explanation: Here we want to add two element but in the given functions we take 3 arguments. So compiler doesn't get the required function(function with 2 arguments)

Question 10:

#include <iostream>
using namespace std;
#define PR(id) cout << "The value of " #id " is " << id
int main()
{
    int i = 10;
    PR(i);
    return 0;
}

Output

The value of i is 10

Explanation: In this program, we are just printing the declared value through a macro. Carefully observe that in macro there is no semicolon(;) used as a termination statement.