提升库 iostream::copy 不起作用
Boost library iostream::copy not working
#include <fstream>
#include <iostream>
#include <boost/iostreams/filtering_streambuf.hpp>
#include <boost/iostreams/copy.hpp>
#include <boost/iostreams/filter/bzip2.hpp>
int main()
{
using namespace std;
using namespace boost::iostreams;
ifstream file("gcc-4.7.2.tar.bz2", ios_base::in | ios_base::binary);
filtering_streambuf<input> in;
in.push(bzip2_decompressor());
in.push(file);
boost::iostreams::copy(in, cout);
system("pause");
return 0;
}
我已经安装了 Boost，如此问题所示：如何在Visual Studio 2010中使用Boost？
我在boost::iostreams::copy(in, cout)语句上出错。
我对 Boost 很陌生，所以我不知道这段代码是对还是错。
我想我做了我应该做的每一件事，我迷失了。
编辑
我已经检查了这个问题：来自 boost：：iostreams：：copy(( 的异常。
我已经更改了我的测试代码以了解我得到什么错误。
#include <fstream>
#include <iostream>
#include <boost/iostreams/filtering_streambuf.hpp>
#include <boost/iostreams/copy.hpp>
#include <boost/iostreams/filter/bzip2.hpp>
int main()
{
using namespace std;
using namespace boost::iostreams;
try {
ifstream file("hello.bz2", ios_base::in | ios_base::binary);
filtering_streambuf<input> in;
in.push(bzip2_decompressor());
in.push(file);
boost::iostreams::copy(in, cout);
}
catch(const bzip2_error& exception) {
int error = exception.error();
if(error == boost::iostreams::bzip2::data_error) {
// compressed data stream is corrupted
cout << "compressed data stream is corrupted";
}
else if(error == boost::iostreams::bzip2::data_error_magic)
{
// compressed data stream does not begin with the 'magic' sequence 'B' 'Z' 'h'
cout << "compressed data stream does not begin with the 'magic' sequence 'B' 'Z' 'h'";
}
else if(boost::iostreams::bzip2::config_error) {
// libbzip2 has been improperly configured for the current platform
cout << "libbzip2 has been improperly configured for the current platform";
}
}
}
它说我得到boost::iostreams::bzip2::config_error.
这是否意味着我错误地安装了 bzip2 过滤器???
因为我使用了一些错误
b2 --toolset=msvc-10.0 -sBZIP2_SOURCE="C:bzip2-1.0.6" --build-type=complete stage
我得到：
C:boost_1_54_0>b2 --toolset=msvc-10.0 -sBZIP2_SOURCE="C:bzip2-1.0.6" --build-t
ype=complete stage
Performing configuration checks
- 32-bit : yes (cached)
- arm : no (cached)
- mips1 : no (cached)
- power : no (cached)
- sparc : no (cached)
- x86 : yes (cached)
error: No best alternative for libs/coroutine/build/allocator_sources
next alternative: required properties: <link>static <target-os>windows <thre
ading>multi
not matched
next alternative: required properties: <link>static <segmented-stacks>on <th
reading>multi
not matched
next alternative: required properties: <link>static <threading>multi
not matched
- has_icu builds : no (cached)
warning: Graph library does not contain MPI-based parallel components.
note: to enable them, add "using mpi ;" to your user-config.jam
- zlib : no (cached)
- iconv (libc) : no (cached)
- iconv (separate) : no (cached)
- icu : no (cached)
- icu (lib64) : no (cached)
- message-compiler : yes (cached)
- compiler-supports-ssse3 : yes (cached)
- compiler-supports-avx2 : no (cached)
- gcc visibility : no (cached)
- long double support : yes (cached)
warning: skipping optional Message Passing Interface (MPI) library.
note: to enable MPI support, add "using mpi ;" to user-config.jam.
note: to suppress this message, pass "--without-mpi" to bjam.
note: otherwise, you can safely ignore this message.
warning: No python installation configured and autoconfiguration
note: failed. See http://www.boost.org/libs/python/doc/building.html
note: for configuration instructions or pass --without-python to
note: suppress this message and silently skip all Boost.Python targets
error: No best alternative for libs/coroutine/build/allocator_sources
next alternative: required properties: <link>static <target-os>windows <thre
ading>multi
not matched
next alternative: required properties: <link>static <segmented-stacks>on <th
reading>multi
not matched
next alternative: required properties: <link>static <threading>multi
not matched
- zlib : no (cached)
error: No best alternative for libs/coroutine/build/allocator_sources
next alternative: required properties: <link>static <target-os>windows <thre
ading>multi
not matched
next alternative: required properties: <link>static <segmented-stacks>on <th
reading>multi
not matched
next alternative: required properties: <link>static <threading>multi
not matched
- zlib : no (cached)
error: No best alternative for libs/coroutine/build/allocator_sources
next alternative: required properties: <link>static <target-os>windows <thre
ading>multi
not matched
next alternative: required properties: <link>static <segmented-stacks>on <th
reading>multi
not matched
next alternative: required properties: <link>static <threading>multi
not matched
- zlib : no (cached)
- zlib : no (cached)
- zlib : no (cached)
error: No best alternative for libs/coroutine/build/allocator_sources
next alternative: required properties: <link>static <target-os>windows <thre
ading>multi
not matched
next alternative: required properties: <link>static <segmented-stacks>on <th
reading>multi
not matched
next alternative: required properties: <link>static <threading>multi
not matched
- zlib : no (cached)
error: No best alternative for libs/coroutine/build/allocator_sources
next alternative: required properties: <link>static <target-os>windows <thre
ading>multi
not matched
next alternative: required properties: <link>static <segmented-stacks>on <th
reading>multi
not matched
next alternative: required properties: <link>static <threading>multi
not matched
- zlib : no (cached)
- zlib : no (cached)
- zlib : no (cached)
error: No best alternative for libs/coroutine/build/allocator_sources
next alternative: required properties: <link>static <target-os>windows <thre
ading>multi
not matched
next alternative: required properties: <link>static <segmented-stacks>on <th
reading>multi
not matched
next alternative: required properties: <link>static <threading>multi
not matched
- zlib : no (cached)
error: No best alternative for libs/coroutine/build/allocator_sources
next alternative: required properties: <link>static <target-os>windows <thre
ading>multi
not matched
next alternative: required properties: <link>static <segmented-stacks>on <th
reading>multi
not matched
next alternative: required properties: <link>static <threading>multi
not matched
- zlib : no (cached)
Component configuration:
- atomic : building
- chrono : building
- context : building
- coroutine : building
- date_time : building
- exception : building
- filesystem : building
- graph : building
- graph_parallel : building
- iostreams : building
- locale : building
- log : building
- math : building
- mpi : building
- program_options : building
- python : building
- random : building
- regex : building
- serialization : building
- signals : building
- system : building
- test : building
- thread : building
- timer : building
- wave : building
...patience...
...patience...
...patience...
...patience...
...patience...
...found 47439 targets...
C:boost_1_54_0>b2 --toolset=msvc-10.0 -sBZIP2_SOURCE="C:bzip2-1.0.6" --build-type=complete stage
Performing configuration checks
- 32-bit : yes (cached)
- arm : no (cached)
- mips1 : no (cached)
- power : no (cached)
- sparc : no (cached)
- x86 : yes (cached)
error: No best alternative for libs/coroutine/build/allocator_sources
next alternative: required properties: <link>static <target-os>windows <threading>multi
not matched
next alternative: required properties: <link>static <segmented-stacks>on <threading>multi
not matched
next alternative: required properties: <link>static <threading>multi
not matched
- has_icu builds : no (cached)
warning: Graph library does not contain MPI-based parallel components.
note: to enable them, add "using mpi ;" to your user-config.jam
- zlib : no (cached)
- iconv (libc) : no (cached)
- iconv (separate) : no (cached)
- icu : no (cached)
- icu (lib64) : no (cached)
- message-compiler : yes (cached)
- compiler-supports-ssse3 : yes (cached)
- compiler-supports-avx2 : no (cached)
- gcc visibility : no (cached)
- long double support : yes (cached)
warning: skipping optional Message Passing Interface (MPI) library.
note: to enable MPI support, add "using mpi ;" to user-config.jam.
note: to suppress this message, pass "--without-mpi" to bjam.
note: otherwise, you can safely ignore this message.
warning: No python installation configured and autoconfiguration
note: failed. See http://www.boost.org/libs/python/doc/building.html
note: for configuration instructions or pass --without-python to
note: suppress this message and silently skip all Boost.Python targets
error: No best alternative for libs/coroutine/build/allocator_sources
next alternative: required properties: <link>static <target-os>windows <threading>multi
not matched
next alternative: required properties: <link>static <segmented-stacks>on <threading>multi
not matched
next alternative: required properties: <link>static <threading>multi
not matched
- zlib : no (cached)
error: No best alternative for libs/coroutine/build/allocator_sources
next alternative: required properties: <link>static <target-os>windows <threading>multi
not matched
next alternative: required properties: <link>static <segmented-stacks>on <threading>multi
not matched
next alternative: required properties: <link>static <threading>multi
not matched
- zlib : no (cached)
error: No best alternative for libs/coroutine/build/allocator_sources
next alternative: required properties: <link>static <target-os>windows <threading>multi
not matched
next alternative: required properties: <link>static <segmented-stacks>on <threading>multi
not matched
next alternative: required properties: <link>static <threading>multi
not matched
- zlib : no (cached)
- zlib : no (cached)
- zlib : no (cached)
error: No best alternative for libs/coroutine/build/allocator_sources
next alternative: required properties: <link>static <target-os>windows <threading>multi
not matched
next alternative: required properties: <link>static <segmented-stacks>on <threading>multi
not matched
next alternative: required properties: <link>static <threading>multi
not matched
- zlib : no (cached)
error: No best alternative for libs/coroutine/build/allocator_sources
next alternative: required properties: <link>static <target-os>windows <threading>multi
not matched
next alternative: required properties: <link>static <segmented-stacks>on <threading>multi
not matched
next alternative: required properties: <link>static <threading>multi
not matched
- zlib : no (cached)
- zlib : no (cached)
- zlib : no (cached)
error: No best alternative for libs/coroutine/build/allocator_sources
next alternative: required properties: <link>static <target-os>windows <threading>multi
not matched
next alternative: required properties: <link>static <segmented-stacks>on <threading>multi
not matched
next alternative: required properties: <link>static <threading>multi
not matched
- zlib : no (cached)
error: No best alternative for libs/coroutine/build/allocator_sources
next alternative: required properties: <link>static <target-os>windows <threading>multi
not matched
next alternative: required properties: <link>static <segmented-stacks>on <threading>multi
not matched
next alternative: required properties: <link>static <threading>multi
not matched
- zlib : no (cached)
Component configuration:
- atomic : building
- chrono : building
- context : building
- coroutine : building
- date_time : building
- exception : building
- filesystem : building
- graph : building
- graph_parallel : building
- iostreams : building
- locale : building
- log : building
- math : building
- mpi : building
- program_options : building
- python : building
- random : building
- regex : building
- serialization : building
- signals : building
- system : building
- test : building
- thread : building
- timer : building
- wave : building
...patience...
...patience...
...patience...
...patience...
...patience...
...found 47439 targets...
您得到的错误实际上是误导性的。
这是因为：
if(boost::iostreams::bzip2::config_error)
。总是计算结果为非零，并给你错误的错误消息！
我没有可用的Windows PC，但我在Mac上测试了"您的"代码(使用Homebrew安装的Boost(，并遇到了同样的错误。
libbzip2 has been improperly configured for the current platform
所以我修复了它并添加了一些错误检查：
#include <fstream>
#include <iostream>
#include <boost/iostreams/filtering_streambuf.hpp>
#include <boost/iostreams/copy.hpp>
#include <boost/iostreams/filter/bzip2.hpp>
#include <boost/filesystem.hpp>
int main()
{
using namespace std;
using namespace boost::iostreams;
char filename[] = "gcc-4.7.2.tar.bz2";
if (!boost::filesystem::exists(filename))
{
cout << "Can't find " << filename << ". Expect errors to follow! " << endl;
}
ifstream file(filename, ios_base::in | ios_base::binary);
filtering_streambuf<input> in;
in.push(bzip2_decompressor());
in.push(file);
try
{
boost::iostreams::copy(in, cout);
}
catch (const bzip2_error& exception)
{
cout << exception.what() << endl;
int error = exception.error();
if (error == bzip2::data_error)
{
cout << "compressed data stream is corrupted";
}
else if (error == bzip2::data_error_magic)
{
cout << "compressed data stream does not begin with the 'magic' sequence 'B' 'Z' 'h'";
}
else if (error == bzip2::config_error)
{
cout << "libbzip2 has been improperly configured for the current platform";
}
else
{
cout << "Error: " << error;
}
cout << endl;
}
}
建
> clang++ 18121908.cpp -lboost_iostreams -lboost_system -lboost_filesystem -o 18121908
跑
> ./18121908
Can't find gcc-4.7.2.tar.bz2. Expect errors to follow!
bzip2 error
Error: -7
为什么-7？因为#define BZ_UNEXPECTED_EOF (-7).Boost称其为bzip2::unexpected_eof。你竟然撞到了溪流的尽头！
制作一个有效的(如果有问题的(bzip2 文件：
> echo 'There should be some compiler stuff in here' > gcc-4.7.2.tar
> bzip2 gcc-4.7.2.tar
重新运行
> ./18121908
There should be some compiler stuff in here
结论
在尝试解压缩之前，您需要检查该文件是否存在。
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