访问冲突读取位置0x00000000 cstrings

Question

From reading other stackoverflow questions I am aware that this error means I am trying to dereference a null pointer. However, I cannot figure out where my code is dereferencing a null pointer. I am trying to set a char* (cstring) to a non-null value, but I get an access violation error. Here is the code:

void Data::setName(char const * const name)
{
    if (this->name)
        delete[] this->name;

    this->name = new char[strlen(name) + 1];    // This is where my code breaks in debug mode
    strcpy(this->name, name);
}

name is a char* variable that gets initialized to null. setName is being called by an overloaded assignment operator:

Data& Data::operator=(const Data& data2)
{
    //if it is a self copy, don't do anything
    if (this == &data2)
        return *this;

    else
    {
        setName(data2.name);    // Here is the call to setName
        return *this;
    }
}

PS For the love of god please don't tell me I shouldn't be using cstrings! I know std::string is better, but this is for a homework assignment that requires cstrings.

Answer 1

If this is the line the code breaks:

this->name = new char[strlen(name) + 1];

then name must be a null pointer, since nothing else is being dereferenced . name is being dereferenced inside the strlen function. Just print the variable value in your debugger and you will be sure.

---

Also, using same name of variable in the setter like this:

struct A
{
    void set(int a){this->a = a;}
    int a;
};

is not a good practice. Just use:

struct A
{
    void set(int na){a = na;}
    int a;
};

or

struct A
{
    void set(int a){a_ = a;}
    int a_;
};