c++ - 将 vector 写入二进制文件并再次读取

Question

我正在尝试将 double vector 写入二进制文件。完成此操作后，我想阅读它。这似乎不起作用。这是代码:

ofstream bestand;
vector<double> v (32);
const char* pointer = reinterpret_cast<const char*>(&v[0]);
size_t bytes = v.size() * sizeof(v[0]);
bestand.open("test",ios::out | ios::binary);
for(int i = 0; i < 32; i++)
{
   v[i] = i;
   cout << i;
   }
bestand.write(pointer, v.size());
bestand.close();
ifstream inlezen;
vector<double> v2 (32);
inlezen.open("test", ios::in | ios::binary);
char byte[8];
bytes = v2.size() * sizeof(v2[0]);
inlezen.read(reinterpret_cast<char*>(&v2[0]), bytes);
for(int i =0; i < 32; i++){

 cout << endl << v2[i] << endl;
 }

这输出“0 1 2 3 0 0 0......”所以它似乎正确读取了前 4 个数字。

Answer 1

此 .write() 获取要写入的字节数，而不是项目数:

bestand.write(pointer, v.size());

由于您已经计算出正确的值，请使用它:

bestand.write(pointer, bytes );