该题为c++ primer plus 书籍中 第七章课后习题
这个double * fill_array(double *pfirst, double *pend)函数体中,
最后的return 返回了一个 --ptemp; 为什么要反回这个,这个位置有点看不懂,反回--ptemp是反回的什么东西?指针地址的自减吗?
另外: if (!cin) // bad input
{
cin.clear();
while (cin.get() != '\n')
continue;
cout << "Bad input; input process terminated.\n";
if(i == 0)
return ptemp;
else
return --ptemp;
}
这里也有 return --ptemp; 希望能有朋友帮我解答疑惑,感激不尽,为何要反回这个呢!
#include
const int Max = 5;
// function prototypes
double * fill_array(double *pfirst, double *pend);
void show_array( double *pfirst, double *pend);
void revalue(double *pfirst, double *pend, double r);
int main()
{
using namespace std;
double properties[Max];
double *pos = fill_array(properties, properties+(Max-1));
show_array(properties, properties+(Max-1));
cout << "Enter revaluation factor: ";
double factor;
cin >> factor;
revalue(properties, properties+(Max-1), factor);
show_array(properties, properties+(Max-1));
cout << "Done.\n";
return 0;
}
double * fill_array(double *pfirst, double *pend)
{
using namespace std;
double temp;
double * ptemp;
int i = 0;
for (ptemp = pfirst; ptemp <= pend; ptemp++)
{
cout << "Enter value #" << (i + 1) << ": ";
cin >> temp;
if (!cin) // bad input
{
cin.clear();
while (cin.get() != '\n')
continue;
cout << "Bad input; input process terminated.\n";
if(i == 0)
return ptemp;
else
return --ptemp;
}
else if (temp < 0) // signal to terminate
break;
pfirst[i] = temp;
i++;
}
return --ptemp;
}
// the following function can use, but not alter,
// the array whose address is pfirst
void show_array( double *pfirst, double *pend)
{
using namespace std;
double * ptemp;
int i = 0;
for (ptemp = pfirst; ptemp <= pend; ptemp++,i++)
{
cout << "Property #" << (i + 1) << ": $";
cout << *ptemp << endl;
}
}
// multiplies each element of ptemp by r
void revalue(double *pfirst, double *pend, double r)
{
double *ptemp;
for (ptemp = pfirst; ptemp <= pend; ptemp++)
*ptemp *= r;
}