分数四则运算器

好的，先弄出个类来，代码如下:

class fraction
{
 private:
 int numerator;         //分子
 int denominator;       //分母
public:
 fraction(int x = 0, int y = 1);
 ~fraction();

 const fraction add(const fraction w);
        const fraction add(int k);    // " + "

        const fraction sub(const fraction w);   // " - "
        const fraction sub(int k);

        const fraction mul(const fraction w);   // " * "
        const fraction mul(int k);

        const fraction div(const fraction w);   // " / "
        const fraction div(int k);

          int commonden(void);
          void show(void);

          //增加的成员函数
          void setn(int x);      //设定分子
          void setd(int y);      //设定分母
          int getn(void)const;
          int getd(void)const;
};

各成员实现如下：

//构造函数
fraction::fraction(int x, int y)
{
 　　numerator = x;
 　　if (y == 0)
 　　{
 　　　　cout << "分母为0" << endl;
 　　　　exit(0);
 　　}
 　　denominator = y;
}

fraction::~fraction()
{
 　　//虚构函数
}
//加法
const fraction fraction::add(const fraction w)
{
    fraction z;
    z.numerator = numerator * w.denominator + w.numerator * denominator;
    z.denominator = denominator * w.numerator;
    return z;
}

//成员函数的重载
//分数 + 整数
const fraction fraction::add(int k)
{
fraction z;
z.numerator = numerator + k*denominator;
z.denominator = denominator;
return z;
}

//减法
const fraction fraction::sub(const fraction w)
{
    fraction z;
    z.numerator = numerator * w.denominator - w.numerator * denominator;
    z.denominator = denominator * w.numerator;
    return z;
}

//成员函数的重载
//分数 - 整数
const fraction fraction::sub(int k)
{
fraction z;
z.numerator = numerator - k*denominator;
z.denominator = denominator;
return z;
}

//乘法
const fraction fraction::mul(const fraction w)
{
    fraction z;
    z.numerator = numerator * w.numerator;
    z.denominator = denominator * w.denominator;
    return z;
}

//成员函数的重载
//分数 * 整数
const fraction fraction::mul(int k)
{
fraction z;
z.numerator = k * numerator;
z.denominator = denominator;
return z;
}

//除法
const fraction fraction::div(const fraction w)
{
    fraction z;
    if (numerator == 0 || w.numerator == 0)
    {
        cout << "两个分子为零的分数相除没有意义" << endl;
        exit(0);
    }
    z.numerator = numerator * w.denominator;
    z.denominator = denominator * w.numerator;
    return z;
}

//成员函数的重载
//分数 / 整数
const fraction fraction::div(int k)
{
　 fraction z;
    if (numerator == 0 || k == 0)
    {
        cout << "两个分子为零的分数相除没有意义" << endl;
        exit(0);
    }
z.numerator = numerator;
z.denominator = k * denominator;
return z;
}

//函数功能：使输出的分数为真分数
int fraction::commonden(void)
{
    int m,n,p;
    m = denominator;
    n = numerator;
    do
    {
        p = m % n;
        m = n;
        n = p;
    }while(p != 0);
    return m;
}

void fraction::show(void)
{
    if (numerator == 0)
    {
        cout << " = 0" << endl;
    }
    else
    {
        if (numerator == denominator)
        {
            cout << " = 1" << endl;
        }
        else
        {
            cout << " = " << numerator/commonden() << "/" << denominator/commonden() << endl;
        }
    }
}

void fraction::setn(int x)      //设定分子
{
numerator = x;
}
void fraction::setd(int y)      //设定分母
{
denominator = y;
}
int fraction::getn(void)const
{
return numerator;
}
int fraction::getd(void)const
{
return denominator;
}

好了，写个主函数来测试下

void main()
{
　　fraction w(6,7),t(9,5),d;

      cout << "(6/7) + (9/5)";
      d = w.add(t);
      d.show();
      cout <<endl;

    cout << "(6/7) + 1";  //       6                  13
    d = w.add(1);           //       -    +   1   =    -
    d.show();                 //       7                   7
    cout <<endl;

    cout << "(6/7) - (9/5)";
    d = w.sub(t);
    d.show();
    cout <<endl;

    cout << "(6/7) - 1";
    d = w.sub(1);
    d.show();
    cout <<endl;

    cout << "(6/7) * (9/5)";
    d = w.mul(t);
    d.show();
    cout <<endl;

    cout << "(6/7) * 2";
    d = w.mul(2);
    d.show();
    cout <<endl;

    cout << "(6/7) / (9/5)";
    d = w.div(t);
    d.show();
    cout <<endl;

    cout << "(6/7) / 2";
    d = w.div(2);
    d.show();
    cout <<endl;
　return ;
}

来看看测试结果吧！