C++ Help with homework!

Hi! I am a beginner to C++ programming and I am completed stumped on one of my homework labs. I will post the homework instructions and what I have done so far. I appreciate any tips or guidance!

Instructions: Prompt the user for a number such as 5 and calculate the square by using pow(variable, 2.0), cube by using pow(variable, 3.0) and 4th power pow(variable, 4.0). Add 5 to the number and repeat the procedure 10 times. In this case up to 50.

What I have done so far:
do
{
cout << "Please enter a number to Square, Cube, and raise to 4th power: ";
cin >> variable;
cout << endl;
cout << "\t" << "Number\tSquare\tCube\t4th Power" << endl;
cout << "\t" << "------\t------\t------\t-------" << endl;
square = pow(variable, 2.0);
cube = pow(variable, 3.0);
fourthP = pow(variable, 4.0);
for (int a = 1; a <= 1; a++) // Outer loop
{
for (int b = 1; b <= 10; b++) // Inner loop
cout << "\t" << variable << "\t" << square << "\t" << cube << "\t" << fourthP << endl;
cout << endl;
}
cout << endl;

cout << "Would you like to continue (Y or N)? ";
cin >> answer;
system("cls");

} while (toupper(answer) == 'Y');

George P (5592)

You want to repeat the calculations 10 times in a single for loop. In the for loop you increment the input variable by 5 each time through the loop.

PLEASE learn to use code tags, they make reading and commenting on source code MUCH easier.

http://www.cplusplus.com/articles/jEywvCM9/
http://www.cplusplus.com/articles/z13hAqkS/

HINT: you can edit your post and add code tags.

Some formatting & indentation would not hurt either

It also would help if your code snippet is complete, copy-able and ready-to-compile. That means including the headers and the main function.

#include <iostream>
#include <cmath>

int main()
{
   char repeat { 'n' };

   do
   {
      std::cout << "Enter a number: ";
      double input { };
      std::cin >> input;

      std::cout << "\n Number\tSquare\tCube\t4th Power\n";
      std::cout << " ------\t------\t------\t-------\n";

      for (int i { 1 }; i <= 10; ++i)
      {
         std::cout << ' ' << input
            << '\t' << std::pow(input, 2.0)
            << '\t' << std::pow(input, 3.0)
            << '\t' << std::pow(input, 4.0) << '\n';

         input += 5;
      }

      std::cout << "\nCalculate a different number? ";
      std::cin >> repeat;
   } while (repeat != 'n');
}

Enter a number: 5

 Number Square  Cube    4th Power
 ------ ------  ------  -------
 5      25      125     625
 10     100     1000    10000
 15     225     3375    50625
 20     400     8000    160000
 25     625     15625   390625
 30     900     27000   810000
 35     1225    42875   1.50062e+06
 40     1600    64000   2.56e+06
 45     2025    91125   4.10062e+06
 50     2500    125000  6.25e+06

Calculate a different number? y
Enter a number: 4

 Number Square  Cube    4th Power
 ------ ------  ------  -------
 4      16      64      256
 9      81      729     6561
 14     196     2744    38416
 19     361     6859    130321
 24     576     13824   331776
 29     841     24389   707281
 34     1156    39304   1.33634e+06
 39     1521    59319   2.31344e+06
 44     1936    85184   3.7481e+06
 49     2401    117649  5.7648e+06

Calculate a different number? n

vnovikov465 (4)

But how do I get the output to look like this (when entering 2):
2 4 8 16
7 49 343 2401
12 144 1728 20736
17 289 4913 83521

(etc...)

jonnin (11331)

you can use int 64 to print the values as integers for a while. But it will overflow at some point, so you may not want that. much past 7100ish will overflow uint64_t to the 5th. you can adjust the double printing to look more like integers as well ... look at the cout format specifiers and play with them if you want. http://faculty.cs.niu.edu/~hutchins/csci241/output.htm

and I see furry already fixed the extra variables :)

Last edited on

George P (5592)

But how do I get the output to look like this (when entering 2)

Enter 2 at the prompt. I simply used 5 and 4 as a test.

Enter a number: 2

 Number Square  Cube    4th Power
 ------ ------  ------  -------
 2      4       8       16
 7      49      343     2401
 12     144     1728    20736
 17     289     4913    83521
 22     484     10648   234256
 27     729     19683   531441
 32     1024    32768   1.04858e+06
 37     1369    50653   1.87416e+06
 42     1764    74088   3.1117e+06
 47     2209    103823  4.87968e+06

Calculate a different number? n

Last edited on

vnovikov465 (4)

Thank you so much! I really appreciate the help.

George P (5592)

and I see furry already fixed the extra variables :)

Without code tags and an incomplete code snippet I didn't see the overuse of variables. I simply coded what I knew would work without the excess memory usage.

againtry (2313)

Another approach for future consideration - using pow is not the best for integers, even though you probably aren't allowed to deviate. <iomanip> gives good control over columns hence <iomanip>, tabs are a student's nightmare and make beginners wonder why C++ is taught.


#include <iostream>
#include <iomanip> // FOR FORMATTING - '\t' is hopelessly frustrating

using namespace std;

int main()
{
    char answer{'Y'};
    
    int col_width{11}; ONLY PLACE REQUIRED TO ADJUST THE WIDTH!
    while ( toupper(answer) == 'Y' )
    {
        cout << "Please enter a number to Square, Cube, and raise to 4th power: ";
        int variable{0};
        cin >> variable;
        
        cout
        << '\n'
        << setw(col_width) << right << "Number"
        << setw(col_width) << right << "Square"
        << setw(col_width) << right << "Cube"
        << setw(col_width) << right << "4th Power\n";
        
        for(int i = 0; i < 4; i++)
            cout << ' ' + std::string(col_width - 1, '-');
        cout << '\n';
        
        long  square = variable * variable;
        long cube =  square * variable;
        long fourthP = cube * variable;
        
        for (int b = 0; b < 10; b++) // Inner loop
        {
            square = variable * variable;
            cube =  square * variable;
            fourthP = cube * variable;
            
            cout
            << setw(col_width) << right << variable
            << setw(col_width) << right << square
            << setw(col_width) << right << cube
            << setw(col_width) << right << fourthP << '\n';
            
            variable += 5;
        }
        cout << '\n';
        
        cout << "Would you like to continue (Y or N)? ";
        cin >> answer;
    }

return 0;
}

Please enter a number to Square, Cube, and raise to 4th power: 18

     Number     Square       Cube 4th Power
 ---------- ---------- ---------- ----------
         18        324       5832     104976
         23        529      12167     279841
         28        784      21952     614656
         33       1089      35937    1185921
         38       1444      54872    2085136
         43       1849      79507    3418801
         48       2304     110592    5308416
         53       2809     148877    7890481
         58       3364     195112   11316496
         63       3969     250047   15752961

Would you like to continue (Y or N)?

lastchance (6980)

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

int main()
{
   #define FORMAT << " " << setw( 12 ) << right <<
   int number;
   cout << "Please enter a number: ";   cin >> number;
   for ( auto head : { "x", "x^2", "x^3", "x^4" } ) cout FORMAT head;
   cout << "\n\n";
   for ( int last = number + 45; number <= last; number += 5 )
   {
      unsigned long long x = 1;
      for ( int power = 1; power <= 4; power++ ) 
      {
         x *= number;
         cout FORMAT x;
      }
      cout << '\n';
   }
}

Please enter a number: 2
            x          x^2          x^3          x^4

            2            4            8           16
            7           49          343         2401
           12          144         1728        20736
           17          289         4913        83521
           22          484        10648       234256
           27          729        19683       531441
           32         1024        32768      1048576
           37         1369        50653      1874161
           42         1764        74088      3111696
           47         2209       103823      4879681

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