如何从内存中读取，就像使用 iostream 从文件中读

问题描述

我将简单的文本文件加载到内存中.我想从内存中读取，就像从这里读取光盘一样:

ifstream 文件；字符串线；file.open("C:\file.txt");如果(文件.is_open()){而(文件.好()){获取行(文件，行)；}}file.close();

但我在内存中有文件.我在内存中有一个地址和这个文件的大小.

我必须做什么才能像上面代码中处理文件一样流畅?

我找到了一个适用于 VC++ 的解决方案，因为 Nim 解决方案仅适用于 GCC 编译器(不过非常感谢.感谢您的回答，我找到了其他答案帮助了我！).

其他人似乎也有类似的问题.我完全按照这里和此处.>

所以要像形成 istream 一样从一块内存中读取，你必须这样做:

class membuf : 公共流缓冲{上市:membuf(char* p, size_t n) {setg(p, p, p + n);}};int main(){char buffer[] = "Hello World!
这是下一行
最后一行";membuf mb(缓冲区，大小(缓冲区))；istream istr(&mb);字符串线；while(getline(istr, line)){cout<<行:["<<线<<"]" <<结束;}}

如果你有 ' ' 新行，就像 Nim 写的那样:

if (*line.rbegin() == '
') line.erase(line.end() - 1);

<小时>

我试图将此内存视为 wistream.有人知道怎么做这个吗?我问了单独的问题 为此.

I have simple text file loaded into memory. I want to read from memory just like I would read from a disc like here:

ifstream file;
string line;

file.open("C:\file.txt");
if(file.is_open())
{
    while(file.good())
    {
        getline(file,line);         
    }
}   
file.close();

But I have file in memory. I have an address in memory and a size of this file.

What I must do to have the same fluency as with dealing with file in the code above?

I found a solution that works on VC++ since Nim solution works only on GCC compiler (big thanks, though. Thanks to your answer I found other answers which helped me!).

It seems that other people have similar problem too. I did exactly as here and here.

So to read from a piece of memory just like form a istream you have to do this:

class membuf : public streambuf
{
    public:
        membuf(char* p, size_t n) {
        setg(p, p, p + n);
    }
};

int main()
{
    char buffer[] = "Hello World!
This is next line
The last line";  
    membuf mb(buffer, sizeof(buffer));

    istream istr(&mb);
    string line;
    while(getline(istr, line))
    {
        cout << "line:[" << line << "]" << endl;
    }
}

EDIT: And if you have ' ' new lines do as Nim wrote:

if (*line.rbegin() == '
') line.erase(line.end() - 1);

I'm trying to treat this memory as as wistream. Does anybody know how to do this? I asked separate question for this.

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