重载“<<<<"”的问题有什么问题？ [英] What's wrong with overloading of "<<"?
问题描述
我用++给出了错误的答案。
我输入了：
1 2 3
4 5 6
7 8 9
显示这是-58993460 * -58993460矩阵。
我不知道为什么。
谁可以帮助我？
I get a wrong answer with a++.
I input a:
1 2 3
4 5 6
7 8 9
It shows " this is a -58993460 * -58993460 matrix.
I don''t konw why.
Who can help me ?
#include<iostream>
using namespace std;
template < typename Type >
class Mtrx
{
private:
int m_iRow , m_iColumn;
Type ** yourmtrx;
public:
Mtrx();
Mtrx(int x , int y);
~Mtrx();
Mtrx ( const Mtrx & m );
Mtrx & operator = ( const Mtrx & m );
Mtrx & operator ++ ();
Mtrx & operator ++ ( int );
template<typename type="">
friend std::ostream & operator << ( std::ostream & os , const Mtrx & m );
template<typename type="">
friend std::istream & operator >> ( std::istream & is , Mtrx & m );
};
template < typename Type >
Mtrx < Type > :: Mtrx()
{
m_iRow=3;
m_iColumn=3;
yourmtrx = new Type* [3];
for (int i=0; i<3; i++)
yourmtrx[i] = new Type [3];
}
template <typename type="">
Mtrx <type> :: Mtrx (int x , int y)
{
m_iRow=x;
m_iColumn=y;
yourmtrx = new Type* [m_iRow];
for (int i=0; i<m_irow;> yourmtrx[i] = new Type [m_iColumn];
}
template <typename type="">
Mtrx <type> :: Mtrx (const Mtrx<type> & m)
{
m_iRow=m.m_iRow;
m_iColumn=m.m_iColumn;
yourmtrx = new Type* [m_iRow];
for (int i=0; i<m_irow;> yourmtrx[i] = new Type [m_iColumn];
for(int i=0; i<m_irow;> for(int k=0; k<m_icolumn;> yourmtrx[i][k] = m.yourmtrx[i][k];
}
template <typename type="">
Mtrx <type> :: ~Mtrx ()
{
delete [] yourmtrx;
}
template <typename type="">
Mtrx<type> & Mtrx <type> :: operator = (const Mtrx<type> & m)
{
if (this == &m)
return * this;
if(m_iRow!=m.m_iRow || m_iColumn!=m.m_iColumn)
{
delete [] yourmtrx;
m_iRow=m.m_iRow;
m_iColumn=m.m_iColumn;
yourmtrx = new Type* [m_iRow];
for (int i=0; i<m_irow;> yourmtrx[i] = new Type [m_iColumn];
}
for(int i=0; i<m_irow;> for(int k=0; k<m_icolumn;> yourmtrx[i][k] = m.yourmtrx[i][k];
return * this;
}
template <typename type="">
Mtrx <type> & Mtrx <type> :: operator ++ ()
{
for(int i=0; i<m_irow;> for(int j=0; j<m_icolumn;> yourmtrx[i][j]++;
return * this;
}
template <typename type="">
Mtrx <type> & Mtrx <type> :: operator ++ (int)
{
Mtrx <type> last = *this;
for (int i=0; i<m_irow;> for (int j=0; j<m_icolumn;> yourmtrx[i][j]++;
return last;
}
template <typename type="">
std::ostream & operator << (std::ostream & os , const Mtrx <type> & m)
{
os << " this is a " << m.m_iRow << " * " << m.m_iColumn << " matrix." << endl;
for (int i=0; i<m.m_irow;> {
for (int j=0; j<m.m_icolumn;> os << m.yourmtrx[i][j] << " ";
os << endl;
}
return os;
}
template <typename type="">
std::istream & operator >> (std::istream & is , Mtrx<type> & m)
{
for (int i=0; i<m.m_irow;> for (int j=0; j<m.m_icolumn;> {
is >> m.yourmtrx[i][j];
if(!is)
cerr<<"input error!"<<endl;
}
return is;
}
int main()
{
Mtrx<int> a;
cin>>a;
cout<<a++;
cout<<++a;
}
推荐答案
Mtrx& operator ++（int）;
Mtrx & operator ++ ( int );
template< typename type =>
Mtrx< type> &安培; Mtrx< type> :: operator ++（int）
{
Mtrx< type> last = * this;
for（int i = 0; i< m_irow;> for（int j = 0; j< m_icolumn;> yourmtrx [i] [j] ++;
最后返回;
}
template <typename type="">
Mtrx <type> & Mtrx <type> :: operator ++ (int)
{
Mtrx <type> last = *this;
for (int i=0; i<m_irow;> for (int j=0; j<m_icolumn;> yourmtrx[i][j]++;
return last;
}
这些都是错误的：postincrement运算符应返回按值其结果，以这种方式更改它们
Those are wrong: the postincrement operator should return by value its result, change them this way
Mtrx operator ++ ( int );
template <typename type>
Mtrx <type> Mtrx <type> :: operator ++ (int)
{
Mtrx <type> last = *this;
for (int i=0; i<m_iRow;i++)
for (int j=0; j<m_iColumn;j++)
yourmtrx[i][j]++;
return last;
}
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