Accelerated C++ Solution to Exercise 4-2

Exercise 4-2

Write a program to calculate the squares of int values up to 100. The program should write two columns: The first lists the value; the second contains the square of that value. Use setw to manage the output so that the values line up in columns.

Solution

To keep the code as simple as possible, for the sake of solving this particular problem, I will have some kind of hard-code values in the codes. Of course, the code can be made more intelligent later on and remove the need of hard-coding!

The setw(n) function returns a value of type streamsize that, when written on an output stream s, has the effect of calling s.width(n).

After doing some experiments in Code::Block I learn that, if (say) the integer width is smaller than n, the outputstream will simply align the numbers to the right, and pad the left side with leading empty spaces. Likewise for strings.

We are asked to output two columns.

Column 1 contains a list of integers defined by this symmetric range [0,100] – i.e. between 0 and 100 inclusively. We therefore require n = 3 for this, so we can fit in the max integer 100.

Column 2 contains a list of integers defined by this symmetric range [0, 10000] – i.e. between 0 and 10000 inclusively. We therefore require n = 6 for this, so we can fit in the max integer 10000 (which takes up a width of 5), plus 1 leading empty space to separate this column from column 1.

The program will look like this:

#include <iostream>
#include <iomanip>

using std::cout;
using std::endl;
using std::setw;

int main()
{
    for (int i = 0; i != 101; ++i)
    {
        cout << setw(3) << i << setw(6) << (i * i) << endl;
    }
}

Result

  0     0
  1     1
  2     4
  3     9
  4    16
  5    25
  6    36
  7    49
  8    64
  9    81
 10   100
 11   121
 12   144
 13   169
 14   196
 15   225
 16   256
 17   289
 18   324
 19   361
 20   400
 21   441
 22   484
 23   529
 24   576
 25   625
 26   676
 27   729
 28   784
 29   841
 30   900
 31   961
 32  1024
 33  1089
 34  1156
 35  1225
 36  1296
 37  1369
 38  1444
 39  1521
 40  1600
 41  1681
 42  1764
 43  1849
 44  1936
 45  2025
 46  2116
 47  2209
 48  2304
 49  2401
 50  2500
 51  2601
 52  2704
 53  2809
 54  2916
 55  3025
 56  3136
 57  3249
 58  3364
 59  3481
 60  3600
 61  3721
 62  3844
 63  3969
 64  4096
 65  4225
 66  4356
 67  4489
 68  4624
 69  4761
 70  4900
 71  5041
 72  5184
 73  5329
 74  5476
 75  5625
 76  5776
 77  5929
 78  6084
 79  6241
 80  6400
 81  6561
 82  6724
 83  6889
 84  7056
 85  7225
 86  7396
 87  7569
 88  7744
 89  7921
 90  8100
 91  8281
 92  8464
 93  8649
 94  8836
 95  9025
 96  9216
 97  9409
 98  9604
 99  9801
100 10000

Reference

Koenig, Andrew & Moo, Barbara E., Accelerated C++, Addison-Wesley, 2000

One thought on “Accelerated C++ Solution to Exercise 4-2”

  1. I used vector and typedef just to improve my skills. This is what I got:
    int main()
    {
    vector sq;

    typedef vector<int>::size_type vc_sz;
    vc_sz size = 100;

    for (vc_sz i = 0; i != size; i++)
    {
    sq.push_back(i+1);
    cout << setw(3) << sq[i] << setw(10) << sq[i] * sq[i] << endl;
    }

    return 0;

    }

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