C ++多項式類，打印成員函數不能很好地與電源配合使用

Question

我正在對兩個多項式進行一些基本運算的多項式類。 除打印功能外，我的其他成員功能運行良好。 這是我的打印成員函數：

void Polynomial::print() const
{
    string plus;//plus is the plus sign in front of every element except the first element
    plus="+";
    int k=0;//k is the power of the each element in the polynomial
    if(coefficient[0]!=0)
        cout<<coefficient[0];

    for(int i=1;i<coefficient.size();i++)
    {

        if(coefficient[i]==-1234)
            break;


        if(coefficient[i]==0)
        {
            k++;
        }
        else if(coefficient[i]==1)
        {
            if(coefficient[i]>=1)
                cout<<plus;
            cout<<"x";
            k++;
        }
        else if(coefficient[i]==-1)
        {
            if(coefficient[i]>=1)
                cout<<plus;
            cout<<"-x";
            k++;
        }
        else
        {
            if(coefficient[i]>=1)
                cout<<plus;
            cout<<coefficient[i]<<"x";
            if(coefficient[i]!=-1234)
            {
                k++;
            }
            else
                break;
            if(k>1)
            {
                cout<<"^"<<k;
            }
        }
    }

    cout<<endl;

    return;
}

現在，如果用戶輸入：1 2 3 1多項式打印為：1 + 2x + 3x ^ 2 + x多項式中的第4個項的k（冪）不為4。小時...仍然不知道哪里出了問題。 謝謝你的幫助！！！

Answer 1

您的for循環應如下所示。 當系數為1或-1時，您不打印功率：

for(int i=1;i<coefficient.size();i++)
{

    if(coefficient[i]==-1234)
        break;


    if(coefficient[i]==0)
    {
        k++;
    }
    else if(coefficient[i]==1)
    {
        if(coefficient[i]>=1)
            cout<<plus;
        cout<<"x";
        k++;
        if(k>1)
        {
            cout<<"^"<<k;
        }

    }
    else if(coefficient[i]==-1)
    {
        if(coefficient[i]>=1)
            cout<<plus;
        cout<<"-x";
        k++;
        if(k>1)
        {
            cout<<"^"<<k;
        }

    }
    else
    {
        if(coefficient[i]>=1)
            cout<<plus;
        cout<<coefficient[i]<<"x";
        if(coefficient[i]!=-1234)
        {
           k++;
        }
        else
            break;
        if(k>1)
        {
            cout<<"^"<<k;
        }
    }
}

Answer 2

問題是您要輸入該塊的最后1 ：

    else if (coefficient[i] == 1)
    {
        if (coefficient[i] >= 1)
            cout << plus;
        cout << "x";
        k++;
    }

破壞了x^power部分。

可能的解決方案可能是：

void print()
{
    string plus;
    plus = "+";
    int k = 0;
    if (coefficient[0] != 0)
        cout << coefficient[0];

    for (int i = 1; i<coefficient.size(); i++)
    {

        if (coefficient[i] == -1234)
            break;


        if (coefficient[i] == 0)
        {
            k++;
        }
        else if (coefficient[i] == 1 && i == 1 /* This prevents entering here afterwards */)
        {
            if (coefficient[i] >= 1)
                cout << plus;
            cout << "x";
            k++;
        }
        else if (coefficient[i] == -1 && i == 1 /* This prevents entering here afterwards */)
        {
            if (coefficient[i] >= 1)
                cout << plus;
            cout << "-x";
            k++;
        }
        else
        {
            if (coefficient[i] >= 1)
                cout << plus;
            cout << coefficient[i] << "x";
            if (coefficient[i] != -1234)
            {
                k++;
            }
            else
                break;
            if (k>1)
            {
                cout << "^" << k;
            }
        }
    }

    cout << endl;
}

這實際上歸結為您對如何打印和格式化多項式感到滿意。

Answer 3

以下內容可能會有所幫助：

void print_polynom(const std::vector<int>& coeffs)
{
    const char* plus = "";
    const char* space = "";

    for (std::size_t i = 0; i != coeffs.size(); ++i) {
        if (coeffs[i] == 0) {
            continue;
        }
        if (coeffs[i] > 0) {
            std::cout << space << plus << space;
        } else {
            std::cout << space << "-" << space;
        }
        plus = "+";
        space = " ";
        if (i == 0 || std::abs(coeffs[i]) != 1) { // to avoid to print 1x^k
            std::cout << std::abs(coeffs[i]);
        }
        if (i == 0) {
            continue;
        }
        std::cout << "x";
        if (i == 1) { // not print x^1
            continue;
        }
        std::cout << "^" << i;
    }
    std::cout << std::endl;
}

現場例子