Question

我编写了一个自定义字符串和向量类。在将字符串添加到向量时偶尔（但始终如一），程序会尝试删除char指针（应该为null），从而导致seg错误。即使一步一步地通过调试器，我也无法弄清楚这个指针通常是不是一个nullptr。

这是我的三个构造函数，用于我的字符串类，以及= overload，它是发生段错误的地方。注意，我确实有一个简单的析构函数，如果它们不为null，则删除数据和tempreturn。

//default constructor
AString::AString(){
    this->length = 0;
    this->cap = 0;
    this->data = nullptr;
    this->tempReturn = nullptr;
}

//constructor with arguments for char*
AString::AString(const char* newData){
    this->length = strlen(newData);
    this->cap = this->length + 1;
    this->data = new char[this->cap];
    this->tempReturn = nullptr;
    for(int i = 0; i < this->length; i ++){
        this->data[i] = newData[i];
    }
    this->data[length] ='\0';
}

//constructor with arguments for passing a string by reference
AString::AString(const AString& newData){
    this->length = newData.length;
    this->cap = this->length + 1;
    this->data = new char[this->cap];
    this->tempReturn = nullptr;
    for(int i = 0; i < this->length; i++){
        this->data[i] = newData.data[i];
    } 
    this->data[length] ='\0';
}

//called with the = string reference
AString& AString::operator= (const AString& newData){
    if(data != nullptr){
        delete[] data;    //This is where it seg faults.
    }

    this->length = newData.length;
    this->cap = newData.length + 1;
    this->data = new char[this->cap];
    for(int i = 0; i < this->length; i ++){
        data[i] = newData.data[i];
    }
    this->data[length] ='\0';

    return *this;
}

在该行，数据应为nullptr，长度应为零。但是，每次在相同的元素，数据填充的位置不包含字符，长度为33. tempreturn，也应该为null，似乎持有无意义的字符

另外作为参考，我的向量构造函数和推回方法导致了seg错误

  //default constructor setting number of elements to empty, and give a 
  //default capacity and initialize array;
 template <class T>
 AVector<T>::AVector(){
     this->cap = 10;
     this->numElements = 0;
     this->data = new T[cap];
 }
 template <class T>
 void AVector<T>::pushBack(T type){
     //add it to the end of the current index
     this->data[numElements] = type;    //line that leads into the segfault
     //increase the tracker for how many elements added
     numElements++;
     //if new element exceeds previously established array
     if(numElements >= cap) {
         increaseCapacity(this->cap * 2);
     }

 }

删除应该为null的指针导致的分段错误

0 个答案: