将文件加载到向量中-Loadingafileintoavector

13  

If you want to avoid reading char by char:

如果你想避免通过char读取char:

if (!file.eof() && !file.fail())
{
    file.seekg(0, std::ios_base::end);
    std::streampos fileSize = file.tellg();
    vec.resize(fileSize);

    file.seekg(0, std::ios_base::beg);
    file.read(&vec[0], fileSize);
}

9  

I think it's something like this, but have no environment to test it:

我认为它是这样的,但没有环境来测试它:

std::copy(std::istream_iterator(file), std::istream_iterator(), std::back_inserter(vec));

Could be you have to play with io manipulators for things like linebreaks/whitespace.

可能你必须使用io操纵器来处理换行/空白等事情。

Edit: as noted in comments, could be a performance hit.

编辑:如评论中所述,可能会受到影响。

6  

use an iterator:

使用迭代器:

#include 

istream_iterator data( file );
istream_iterator end;
vec.insert( std::back_inserter(vec), data, end );

4  

Another approach, using rdbuf() to read the whole file to a std::stringstream first:

另一种方法,使用rdbuf()将整个文件首先读取到std :: stringstream:

#include 
#include 
#include 
#include 

// for check:
#include 
#include 
#include 

int main() {
   std::ifstream file("test.cc");
   std::ostringstream ss;
   ss < vec(s.begin(), s.end());

   // check:
   std::copy(vec.begin(), vec.end(), std::ostream_iterator(std::cout));
}

1  

There were lots of good responses. Thanks all! The code that I have decided on using is this:

有很多好的回应。谢谢大家!我决定使用的代码是这样的:

std::vector vec;
std::ifstream file;
file.exceptions(
    std::ifstream::badbit
  | std::ifstream::failbit
  | std::ifstream::eofbit);
//Need to use binary mode; otherwise CRLF line endings count as 2 for
//`length` calculation but only 1 for `file.read` (on some platforms),
//and we get undefined  behaviour when trying to read `length` characters.
file.open("test.txt", std::ifstream::in | std::ifstream::binary);
file.seekg(0, std::ios::end);
std::streampos length(file.tellg());
if (length) {
    file.seekg(0, std::ios::beg);
    vec.resize(static_cast(length));
    file.read(&vec.front(), static_cast(length));
}

Obviously, this is not suitable for extremely large files or performance-critical code, but it is good enough for general purpose use.

显然,这不适用于超大文件或性能关键代码,但它足以用于通用目的。