用类实现集合的交集，出错了，（>_<)...

[MAXDAVID]

#include <iostream>
using namespace std;

class set
{
int*element;
int number;
public:
set () {element=NULL;number=0;}
set(const int e[],int n)
{
element=new int[n];
int*temp=element;
for(int i=0;i<n;i++)
*temp++=e[i];
number=n;
}
set(const set & t)
{
number=t.number;
element=t.element;
}
int GetOneAt(int i) const //得到第i个数
{
int*temp=element;
return *(temp+i);
}
int isMemberOf(int t) const
{
for(int index=0;index<number;index++)
if(GetOneAt(index)==t)
return index+1;
return 0;
}
void AddOne(int t)
{
if(isMemberOf(t))
return;
else
{
int*temp=element+number;
*temp=t;
number++;
}
}
set InSection(const set & B) const
{
set C;
for (int index=0; index<number; index++)
{
int i=GetOneAt(index);
if (B.isMemberOf(i))
C.AddOne(i);
}
return C;
}
void Print() const
{
int*temp=element;
for(int i=1;i<=number;i++)
cout<<*temp++<<" ";
}
};

void main()
{
int a[3]={1,2,3},b[4]={1,5,6,7};
set A(a,3);
set B(b,4);
set C(A.InSection(B));
C.Print();
C.PrintN();
}

我刚学C++，上面的程序我想了好几天都没做成，一直出错....

[luciferisnotsatan]

出什么错？说一下

[MAXDAVID]

程序的算法应该没有错，但运行的时候就会显示“Cpp.exe已停止工作”，程序就运行不了....

[柯本]

你的默认构造有问题:
set () {element=NULL;number=0;}
在
set InSection(const set & B) const 函数中

set C; //element=NULL
然后在
C.AddOne(i);
int*temp=element+number; ///element==NULL,非法地址

[MAXDAVID]

但默认构造函数要怎么定义呢？请具体说一下...

[赵4老师]

仅供参考

#include <algorithm>
#include <iostream>
#include <functional>
#include <cstring>
using namespace std;
int main() {
    char *Alphabet = "abcdefghijklmnopqrstuvwxyz" ;
    char *Vowels   = "aeiou" ;
    char *AlphaNum = "0123456789abcdef" ;
    char result[45] ;
    char *last ;

    int lenA  = strlen(Alphabet) ;
    int lenV  = strlen(Vowels  ) ;
    int lenAN = strlen(AlphaNum) ;

    cout << "Alphabet = " << Alphabet << endl ;
    cout << "Vowels   = " << Vowels   << endl ;
    cout << "AlphaNum = " << AlphaNum << endl ;

    cout << "\nusing non-predicate versions" << endl ;

    //non-predicate set_difference
    last = set_difference(Alphabet, Alphabet+lenA,
                          AlphaNum, AlphaNum+lenAN,
                          result) ;
    *last = 0 ;
    cout << "set_difference(Alphabet, AlphaNum) =  " << result << endl ;

    //non-predicate set_intersection
    last = set_intersection(Alphabet, Alphabet+lenA,
                            AlphaNum, AlphaNum+lenAN,
                            result) ;
    *last = 0 ;
    cout << "set_intersection(Alphabet, AlphaNum) =  " << result << endl ;

    //non-predicate set_symmetric_difference
    last = set_symmetric_difference(Alphabet, Alphabet+lenA,
                                    Vowels  , Vowels  +lenV,
                                    result) ;
    *last = 0 ;
    cout << "set_symmetric_difference(Alphabet, Vowels) =  " << result << endl ;

    //non-predicate set_union
    last = set_union(Alphabet, Alphabet+lenA,
                     AlphaNum, AlphaNum+lenAN,
                     result) ;
    *last = 0 ;
    cout << "set_union(Alphabet, AlphaNum) =  " << result << endl ;

    cout << "\nusing predicate versions" << endl ;

    //predicate set_difference
    last = set_difference(Alphabet, Alphabet+lenA,
                          AlphaNum, AlphaNum+lenAN,
                          result  , less<char>()) ;
    *last = 0 ;
    cout << "set_difference(Alphabet, AlphaNum) =  " << result << endl ;

    //predicate set_intersection
    last = set_intersection(Alphabet, Alphabet+lenA,
                            AlphaNum, AlphaNum+lenAN,
                            result  , less<char>()) ;
    *last = 0 ;
    cout << "set_intersection(Alphabet, AlphaNum) =  " << result << endl ;

    //predicate set_symmetric_difference
    last = set_symmetric_difference(Alphabet, Alphabet+lenA,
                                    Vowels  , Vowels  +lenV,
                                    result  , less<char>()) ;
    *last = 0 ;
    cout << "set_symmetric_difference(Alphabet, Vowels) =  " << result << endl ;

    //predicate set_union
    last = set_union(Alphabet, Alphabet+lenA,
                     AlphaNum, AlphaNum+lenAN,
                     result  , less<char>()) ;
    *last = 0 ;
    cout << "set_union(Alphabet, AlphaNum) =  " << result << endl ;

    return 0 ;
}

[MAXDAVID]

楼上大神水平好高！！！不过非常感谢！

[程序员小迷]

InSection函数里调用AddOne函数，
InSection函数里构造了临时对象Set C; 但是C什么都没有，element和number的值都是0， 导致C.AddOne(i)因为空指针挂掉