使用大小为8的未初始化值 [英] Use of uninitialised value of size 8

问题描述

我正在实现的fwd_iterator有一个非常奇怪的问题：

I'm having a quite strange problem with the fwd_iterator that I'm implementing:

如果我在类中定义的方法中使用迭代器，它们可以工作，但是如果我创建一个全局范围的方法，我使用迭代器，valgrind说我试图访问未初始化的内存。

if I use the iterators in methods defined inside the class, they work, but if I create a method with global scope in which I use iterators, valgrind says that I'm attempting to access to uninitialised memory.

似乎在类外创建的迭代器无法读取类的私有属性（即使使用公共方法创建这样做）。

It seems like iterators created outside the class cannot read a private attribute of the class (even with public methods created to do this).

这是全球范围的方法：

template<typename T, class Pred>
int evaluate(SparseMatrix<T> &sm, Pred pred){
    typename SparseMatrix<T>:: iterator begin, end;
    int count=0;
    begin=sm.begin();
    end=sm.end();
    while(begin!=end){
            if(pred(*(begin->data))) count++;
            begin++;
    }
    int dcount=0;
    if(pred(sm.getDef())) dcount = ((sm.getRows() * sm.getCols()) - sm.getSize());
    return count+dcount;
}

这是内部类方法：

void print_it() {
    iterator x=begin();
    iterator y=end();
    int i=1;
    while(x!=y){ 
        cout<<i<<".("<<(x->i)<<","<<(x->j)<<")="<<*(x->data)<<endl;
        ++x;
        i++;
    }
    if(x==y) cout<<"End."<<endl;
    cout<<endl;
}

解决：迭代器类有两个属性，value_type val和sm，指向类本身的指针。在operator =（const iterator& other）中，我忘了在val = other.val之后添加; sm = other.sm;行。

Solved: iterator class has two attributes, value_type val, and sm, a pointer to the class itself. In operator=(const iterator& other) I forgot to add after val=other.val; the sm=other.sm; line.

现在一切正常！

推荐答案

迭代器类有两个attributes，value_type val和sm，指向类本身的指针。在operator =（const iterator& other）中，我忘了在val = other.val之后添加; sm = other.sm; line。

iterator class has two attributes, value_type val, and sm, a pointer to the class itself. In operator=(const iterator& other) I forgot to add after val=other.val; the sm=other.sm; line.

现在一切正常！

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