Fstream的tellg / seekg返回比预期更高的值 [英] Fstream's tellg / seekg returning higher value than expected

问题描述

为什么失败，它应该是简单和工作？

  fisier.seekg（0，ios :: end）; 
 long lungime = fisier.tellg（）; 
  

这会返回比文件大的值，导致错误

  char * continut = new char [lungime];任何想法可能是什么问题？
  
 p>我也试图计数到文件结束一个字符，一次，提供了相同的结果，比预期更高的数字。但是在使用getline（）一次读取一行时，它工作，没有额外的空格... 
解决方案
在猜测，你打开文件的翻译模式，可能在Windows下。当你只是寻找到文件的结尾，当前位置不考虑行末翻译。一行的结束（在外部文件中）用\r\\\
对标记 - 但是当你读它时，它被转换为一个\\\
。当您使用 getline 一次读取一行时， \\\
 的所有内容也会被丢弃，因此即使在没有从外部到内部表示的翻译的系统（例如Unix / Linux）上，你仍然可以期望那些具有不同的大小。
 
 
 
真的忘记了 new [] 存在。如果要将整个文件读入字符串，请尝试这样的：
  std :: stringstream continut; 
 continut<< fisier.rdbuf（）; 
  
   std :: string 包含来自文件的数据。
 
Why does this fail, it's supposed to be simple and work ? 
fisier.seekg(0, ios::end);
long lungime = fisier.tellg();
This returns a larger value than that of the file resulting in a wrong
char *continut = new char[lungime];
Any idea what the problem could be ?

I also tried counting to the end of the file one char at a time, that rendered the same result, a higher number than expected. But upon using getline() to read one line at a time, it works, there are no extra spaces... 
解决方案
At a guess, you're opening the file in translated mode, probably under Windows. When you simply seek to the end of the file, the current position doesn't take the line-end translations into account. The end of a line (in the external file) is marked with the pair "\r\n" -- but when you read it in, that's converted to just a "\n". When you use getline to read one line at a time, the \ns all get discarded as well, so even on a system (e.g. Unix/Linux) that does no translation from external to internal representation, you can still expect those to give different sizes.

Then again, you should really forget that new [] exists at all. If you want to read an entire file into a string, try something like this:
std::stringstream continut;
continut << fisier.rdbuf();
continut.str() is then an std::string containing the data from the file.

                        
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