无法使用ifstream将txt文件的最后一部分写入cout [英] Can't write the last part of a txt file to cout using ifstream

问题描述

下面的代码将打印我使用的示例文本文件中的所有文本，除了它的最后一个小片段。我认为这与eof或字节大小有关系我使用不工作，因为我期望。

The code below will print all of the text from the sample text file I'm using except for the last little snippet of it. I think this has something to do with the eof or the byte size I'm using not working as I expect.

#include <iostream>
#include <fstream>

using namespace std;

int main(int argc, char* argv[]){
int length;
char* buffer;

//get file stream and open local file.
ifstream stream;
stream.open("SampleFile.txt", ios::binary);
stream.seekg(0, ios::end);
length = stream.tellg();
stream.seekg(0, ios::beg);

//read stream 1024 bytes at a time until all bytes of file are used
buffer = new char[1024];
bool eof = false;
while(!eof)
{
    stream.read(buffer, 1024);
    cout.write(buffer, 1024);
    if(stream.eof())
        eof = true;
    //cout << i << endl;
    //cout.write(buffer, 1024);
}

stream.close();
delete[] buffer;
return 0;
}

我缺少什么？

推荐答案

正如你已经知道的，你的缓冲区大小不正确。另一件事是读取少于1024个字符（如果您的文件没有完全 n * 1024 字节，则会发生在最后）。利用 istream :: gcount 的优势，它提供了最后一次读取的字符数：

As you already know, you have a wrong size of buffer. The other thing is the read of less than 1024 characters (going to happen at the end if your file doesn't have exactly n*1024 bytes). Take the advantage of istream::gcount which gives you number of characters extracted by last read:

char buffer[1024];
while(stream)
{
    stream.read(buffer, 1024);
    cout.write(buffer, stream.gcount());
}

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