我需要写入/读取包含 std::map 的文件。该文件必须在程序启动时读取(如果存在)。我正在使用 boost 的 fstream,但我得到了这个:
"terminate called after throwing an instance of 'boost::archive::archive_exception'
what(): input stream error"
好吧,我真的不知道发生了什么..这些是我的台词:
map<int64_t, int64_t> foo;
filesystem::path myFile = GetWorkingDirectory() / "myfile.dat";
[...............] // some code
filesystem::ifstream ifs(myFile);
archive::text_archive ta(ifs);
if (filesystem::exists(myFile)
{
ta >> foo; // foo is empty until now, it's fed by myFile
ifs.close();
}
我做错了什么?任何想法?
谢谢。
附言请注意,之后的几行,我需要执行相反的操作:将 std::map foo 写入 myfile.dat。
编辑:如果我使用 std::ifstream,一切正常,将文件保存在我运行应用程序的同一目录中。但是使用 boost 和他的路径,出了点问题。
我有点生气。您显然正在使用 Boost Serialization(archive/
header 是该库的一部分),但不知何故您什么也没说。因为它很容易演示:
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#include <boost/archive/text_iarchive.hpp>
#include <boost/archive/text_oarchive.hpp>
#include <boost/serialization/map.hpp>
#include <boost/filesystem.hpp>
#include <boost/filesystem/fstream.hpp>
using namespace boost;
int main() {
std::map<int64_t, int64_t> foo;
filesystem::path myFile = filesystem::current_path() / "myfile.dat";
if (filesystem::exists(myFile))
{
filesystem::ifstream ifs(myFile/*.native()*/);
archive::text_iarchive ta(ifs);
ta >> foo; // foo is empty until now, it's fed by myFile
std::cout << "Read " << foo.size() << " entries from " << myFile << "\n";
} else {
for (int i=0; i<100; ++i) foo.emplace(rand(), rand());
filesystem::ofstream ofs(myFile/*.native()*/);
archive::text_oarchive ta(ofs);
ta << foo; // foo is empty until now, it's fed by myFile
std::cout << "Wrote " << foo.size() << " random entries to " << myFile << "\n";
}
}
打印
Wrote 100 random entries to "/tmp/myfile.dat"
第二次运行时:
Read 100 entries from "/tmp/myfile.dat"