我将如何设置为空;C++设置空指针?
LookupTable<Product *> table;
一切,我试着说
1智能感知:没有合适的构造存在,从 “INT” 转换为 “LookupTable中”
这里是查找表:
#ifndef LOOKUPTABLE_H
#define LOOKUPTABLE_H
#include <iostream>
#include <string>
using namespace std;
#define MAXRANGE 10
template <class T>
class LookupTable
{
private:
T *aptr[MAXRANGE];
int rangeStart[MAXRANGE];
int rangeEnd[MAXRANGE];
int numRanges;
public:
T defaultValue;
bool failedRangeCheck;
std::string failReason;
// Constructor
LookupTable()
{
numRanges = 0;
defaultValue = T();
}
void addRange(int start, int end)
{
std::cout << "Created a new range... Start: " << start << "/End: " << end << endl;
failedRangeCheck = false;
//lines omitted because not working anyway
if (!failedRangeCheck)
{
//set ranges
rangeStart[numRanges] = start;
rangeEnd[numRanges] = end;
//build new generic array with end-start+1 positions
//set pointer to point to it
aptr[numRanges] = new T[ end - start + 1 ];
numRanges++;
}
else
{
std::cout << "Range overlapped another range." << endl;
std::cout << failReason << endl;
}
}
T &operator[](int value) // Overloaded [] operator
{
for (int i = 0; i < numRanges; i++)
{
if ((value >= rangeStart[i]) && (value <= rangeEnd[i]))
{
return aptr[i][value - rangeStart[i]];
}
}
return defaultValue;
}
~LookupTable()
{
delete[] aptr;
numRanges = 0;
}
};
#endif
设置*什么*为null?你有一个未知的模板类型'LookupTable'的对象,这是以前从未有人听说过的。你如何期望任何人知道如何“设置”这个对象“为空”?甚至什么“设置为空”在应用于此对象时应该表示什么? – AnT 2010-11-04 01:16:22
这似乎是他以前的问题的延伸:http://stackoverflow.com/questions/4092747/c-pointers-to-objects-type-checking我相信他真正需要的完整答案只有在那里的背景... – TheUndeadFish 2010-11-04 01:43:39
它是,因为我从来没有得到一个工作或对我的情况有意义的答案...我被指出正确的方向,但需要更多的帮助 – JustinY17 2010-11-04 01:47:09