写作矢量＆lt;＆双GT;二进制文件并重新阅读它

问题描述

我想双打的载体写入到一个二进制文件。
这样做之后，我想读它。这似乎并没有工作。
这里是code：

I'm trying to write a vector of doubles to a binary file.After doing this I want to read it. This doesn't seem to work.Here is the code:

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;
 }

这个输出0 1 2 3 0 0 0 ......如此看来它正确读取第4个号码。

This outputs "0 1 2 3 0 0 0......" so it seems it reads the first 4 numbers correctly.

推荐答案

本 .WRITE（）需要数量的字节的，而不是数的项目的写：

This .write() takes the number of bytes, not the number of items to write:

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

既然你已经计算出正确的值，使用它：

Since you've already computed the correct value, use it:

bestand.write(pointer, bytes );

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