c++ - Why are all the strings I read ending up equal when I print them?

Question

I am learning C++ and there is a question in the book.

Q: Write a program that defines a vector of pointers to strings. Read the vector, printing each string and its corresponding size.

Code:

vector<string*> v;
string str;
cout<<"Enter your string:"<<endl;

while(cin >> str)                            // input 
{
          string *ps=&str;
          v.push_back(ps);
}

vector<string*>::iterator iter=v.begin();
while( iter!=v.end())                         // output
   cout<< **iter++<<" "<<(**iter).size()<<endl;

When I input "a sd fgh", I expect the output to be "a 1; sd 2; fgh 3"; but the output is "fgh 3; fgh 3; fgh 3." Anyone know where is going wrong?

Answer 1

你得到相同的输出，因为你所有的字符串都指向同一个地方——即你的str变量。您应该使用缓冲区str的数据创建新字符串，如下所示：

std::string *ps = new string(str);

delete ptr完成此操作后，当您不再需要字符串时，不要忘记通过在函数末尾调用每个字符串指针来删除分配的字符串。

Answer 2

我会给你一个线索：std::string *ps = &str这是一个非常糟糕的主意。每个指针都需要自己的内存。