C++ Array function and manipulation

Question

Okay I have a lab assignment for class to make a program that is suppose to do a number of things: 1. A void function named convertWeight converts a weight in pounds (type int) and ounces to the equivalent weight in kilograms (type int) and grams

A void function named showArray that takes two parameters: one array parameter of base type int, and one call-by-value parameter for the size of the array parameter. This function simply prints out all elements of the array parameter, where two consecutive elements are separated by a horizontal tab.
In the main() function definition, do the followings:

a. declare an array named pounds of 10 integers, initializing its first 3 elements to the following values: 1, 5, 10, and auto-initializing the remaining elements to 0.

b. write a for-loop that reads in 7 weights in pounds, storing the entered values to the last 7 elements of the array pounds.

c. print out one prompt line “The entire list of weight:” and then call the function showArray to display the entire array pounds.

d. write another for-loop that calls the function convertWeight to convert each weight in pounds given in the array pounds to the equivalent weight in kilograms and grams.

This what I came up with:

#include <iostream>
using namespace std;


void convertWeight(int pounds, double ounces, int& kg, double& grams);
//Preconditions: parameters pounds and ounces are nonnegative numbers, representing a     weight in pounds and ounces
//Postcondition: parameters kg and grams will be set to values of the equivalent weight   in kilograms and grams
void showArray(int pounds[10]);

int main()
{
        int pounds[10]={1, 5, 10}, i, a, kg;
    double ounces, grams;

    cout << "Enter 7 additional weights in pounds: \n";
    cin >> pounds[3];

    for(i = 4; i < 10; i++)
    {
        cin >> pounds[i];
    }

    cout << "The entire list of weights: \n";

    showArray(pounds[10]);

    for(a = 0; a < 10; a++)
    {
        pounds = pounds[a];
        convertWeight(pounds, ounces, kg, grams);
        cout << pounds[a] << " pounds = " << kg << " kgs and " << grams << "    grams";
    }


    return 0;
}

void showArray(int pounds[10])
{
    cout << pounds[0] << "     " << pounds[1] << "     " << pounds[2] << "     " <<  pounds[3] << "     " << pounds[4] << "     " << pounds[5] << "     "
     << pounds[6] << "     " << pounds[7] << "     " << pounds[8] << "     " <<   pounds[9] << "     " << pounds[10] << "     " ;
}

//Do NOT modify this function definition
void convertWeight(int pounds, double ounces, int& kg, double& grams)
{
  const double KGS_PER_POUND =  0.45359237;
  const double OUNCES_PER_POUND = 16.0;
  const double GRAMS_PER_KG = 1000.0;

  double totalKgs;
  totalKgs = (pounds + ounces/OUNCES_PER_POUND)*KGS_PER_POUND;
  kg = static_cast<int>(totalKgs);
  grams = (totalKgs - kg)*GRAMS_PER_KG;
}

I am new to this Array thing and I cant get what my book is telling me. Could you please point out what it is that is wrong with my program and tell me why so I know.

here is my error list:

1>c:\users\mackiller\documents\visual studio 2010\projects\lab12\lab12\lab12.cpp(30):  error C2664: 'showArray' : cannot convert parameter 1 from 'int' to 'int []'
1>          Conversion from integral type to pointer type requires reinterpret_cast, C-style cast or function-style cast
1>c:\users\mackiller\documents\visual studio 2010\projects\lab12\lab12\lab12.cpp(34): error C2440: '=' : cannot convert from 'int' to 'int [10]'
1>          There are no conversions to array types, although there are conversions to references or pointers to arrays
1>c:\users\mackiller\documents\visual studio 2010\projects\lab12\lab12\lab12.cpp(35): error C2664: 'convertWeight' : cannot convert parameter 1 from 'int [10]' to 'int'
1>          There is no context in which this conversion is possible

Any help givin will be appreciated!

pounds = pounds[a]; - You can't assign a single array element into the array variable itself. Just define a new int variable with a non conflicting name. — Leeor
– Leeor, Commented Nov 21, 2013 at 21:42
I was to use the for loop's variable "a" that changes value every single loop — user2910452
– user2910452, Commented Nov 21, 2013 at 21:43
Why do so many of the C++ questions on Stack Overflow have some kind of War Games inspired 1980s-style command-line interface? Also, use std::array and not C arrays whenever possible. — tadman
– tadman, Commented Nov 21, 2013 at 21:49

Zac Howland · Accepted Answer · 2013-11-21 21:47:49Z

2

c:\users\mackiller\documents\visual studio 2010\projects\lab12\lab12\lab12.cpp(30): error C2664: 'showArray' : cannot convert parameter 1 from 'int' to 'int []' 1>
Conversion from integral type to pointer type requires reinterpret_cast, C-style cast or function-style cast

The problem is here

showArray(pounds[10]);

That will not pass an array, it will attempt to access the 11th element of the array (and invoke undefined behavior), and pass that to showArray (which takes a pointer as an argument). What you want to do there is:

showArray(pounds);

1>c:\users\mackiller\documents\visual studio 2010\projects\lab12\lab12\lab12.cpp(34): error C2440: '=' : cannot convert from 'int' to 'int [10]' 1> There are no conversions to array types, although there are conversions to references or pointers to arrays

This problem is here:

pounds = pounds[a];

You are attempting to assign an int to an array. You don't need that line at all:

convertWeight(pounds[a], ounces, kg, grams);

Which also fixes this error:

1>c:\users\mackiller\documents\visual studio 2010\projects\lab12\lab12\lab12.cpp(35): error C2664: 'convertWeight' : cannot convert parameter 1 from 'int [10]' to 'int' 1>
There is no context in which this conversion is possible

answered Nov 21, 2013 at 21:47

Zac Howland

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1 Comment

user2910452 Over a year ago

Thank you very much! I understand now. I seem to be heading in the wrong direction. Also one more thing. Since it fixed my errors it gave me new ones: error C2109: subscript requires array or pointer type it gave me this error 10 times in a row in the function showArray. I seem to have done this program wrong. Is there another way or a fix to the way im trying to print out the arrays?

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