c++ - 在抛出 'std::length_error' 实例后调用的 cout 结果终止

Question

当我运行我的程序时，它因以下错误而崩溃:

terminate called after throwing an instance of 'std::length_error' what(): basic_string::_S_create Aborted (core dumped)

我用下面的代码得到它:

#include <iostream>
#include <string>
using namespace std;

class Cargo
{
    string nm;
public:
    Cargo(const string& name): nm(name)
    {

    }
    Cargo& operator=(const Cargo& )
    {
        cout<<"inside Cargo::operator=()"<<endl;
        return *this;
    }

    friend ostream& operator<<(ostream& os, const Cargo& ca)
    {
        return os<<"Cargo name: "<<ca.nm;
    }
};

class Truck
{
    Cargo b;
    string name;
public:
    Truck(const string& nm):b("Cargo" + name)
    {
        name = nm;
    }

    void print()
    {
        cout << "name: " << name << endl;
        cout << b << endl;
    }
};

int main()
{
    Truck a("Truck a"), b("Truck b");
    a = b;
    a.print();
    b.print();
}///~:

Answer 1

在您的 Truck 构造函数中:

Truck(const string& nm):b("Cargo" + name)
{
    name = nm;
}

您正在将 Truck 类的 name 属性作为参数发送给 b，该属性未初始化。我猜您想改为传递 nm 参数:

Truck(const string& nm):b("Cargo" + nm)
{
    name = nm;
}