C ++：每次我读fstream我有1个额外的字符在结束 [英] C++: Everytime I read in by fstream I got 1 extra character at the end

问题描述

编辑：

$

每次我读fstream的时候，我得到了一个额外的字符， b $ b

  ifstream readfile（inputFile）; 
 ofstream writefile（outputFile）; 
 char c; 
 while（！readfile.eof（））{
 readfile>> C; 
 // c = shiftChar（c，RIGHT，shift）; 
 writefile<< C; 
} 
 readfile.close（）; 
 writefile.close（）; 
  

解决方案

这通常是由于文件结尾测试错误。您通常想要执行以下操作：

  while（infile>> variable）... 
  

或：

  while std :: getline（infile，whatever））... 
  

但不是：

  while（infile.good（））... 
  

或：

  while（！infile.eof（））... 
  

编辑：前两个读取，检查它是否失败，如果是，退出循环。后两个尝试读取，处理什么是读取，然后如果先前的尝试失败，则在下一个迭代上退出循环。

Edit2：要轻松地将一个文件复制到另一个文件，请考虑使用这样的文件：

  //打开文件：
 ifstream readfile（inputFile）; 
 ofstream writefile（outputFile）; 
 
 //做拷贝：
 writefile<< readfile.rdbuf（）; 
  

Everytime I read in by fstream I got 1 extra character at the end, How can I avoid this?

EDIT:

ifstream readfile(inputFile);
ofstream writefile(outputFile);
char c;
while(!readfile.eof()){
      readfile >> c;
      //c = shiftChar(c, RIGHT, shift);
      writefile << c;
}
readfile.close();
writefile.close();

解决方案

This typically results from testing for the end of file incorrectly. You normally want to do something like:

while (infile>>variable) ...

or:

while (std::getline(infile, whatever)) ...

but NOT:

while (infile.good()) ...

or:

while (!infile.eof()) ...

Edit: The first two do a read, check whether it failed, and if so exit the loop. The latter two attempt a read, process what was "read", and then exit the loop on the next iteration if the previous attempt failed.

Edit2: to copy one file to another easily, consider using something like this:

// open the files:
ifstream readfile(inputFile);
ofstream writefile(outputFile);

// do the copy:
writefile << readfile.rdbuf();

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