即使它在具有足够内存的 64 位 linux 机器上运行，我也无法超出 stringstream 的 4GB 限制。
下面的测试代码（阅读您的评论后修改）核心转储后 4GB。
从 gdb 跟踪来看，stringstream 使用默认的 std::char_traits，其中 int_type 设置为 32 位 int，而不是 64 位 size_t。有什么建议可以解决吗？
#include <stdint.h>
#include <iostream>
#include <sstream>
#include <math.h>
using namespace std;
int main(int narg, char** argv)
{
string str;
stringstream ss;
const size_t GB = (size_t)pow(2, 30);
str.resize(GB, '1');
cerr << "1GB=" << str.size()
<< ", string::max_size=" << str.max_size()/GB << "GB"
<< ", sizeof(int)=" << sizeof(int)
<< ", sizeof(int64_t)=" << sizeof(int64_t)
<< ", sizeof(size_t)=" << sizeof(size_t)
<< endl;
string().swap(str);
str.resize(6*GB, '6');
cerr << "str.size()=" << (str.size() / GB) << "GB allocated successfully"
<< ", ended with " << str.substr(str.size()-5, 5) << endl;
string().swap(str);
str.resize(GB/4, 'Q');
cerr << "writing to stringstream..." << std::flush;
for (int i = 0; i < 30; ++i) {
ss << str << endl;
cerr << double(ss.str().size())/GB << "GB " << std::flush;
}
cerr << endl;
exit(0);
}
输出是：
1GB=1073741824, string::max_size=4294967295GB, sizeof(int)=4, sizeof(int64_t)=8, sizeof(size_t)=8
str.size()=6GB allocated successfully, ended with 66666
writing to stringstream...0.25GB 0.5GB 0.75GB 1GB 1.25GB 1.5GB 1.75GB 2GB 2.25GB 2.5GB 2.75GB 3GB 3.25GB 3.5GB 3.75GB Segmentation fault (core dumped)
gdb 堆栈跟踪是：
(gdb) where
#0 0x00002aaaaad5e0c1 in std::basic_stringbuf<char, std::char_traits<char>, std::allocator<char> >::overflow(int) () from /usr/lib64/libstdc++.so.6
#1 0x00002aaaaad62cbd in std::basic_streambuf<char, std::char_traits<char> >::xsputn(char const*, long) () from /usr/lib64/libstdc++.so.6
#2 0x00002aaaaad5657d in std::basic_ostream<char, std::char_traits<char> >& std::operator<< <char, std::char_traits<char>, std::allocator<char> >(std::basic_ostream<char, std::char_traits<char> >&, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) () from /usr/lib64/libstdc++.so.6
#3 0x000000000040112b in main ()
二进制文件似乎是 64 位的。
$ file a.out
a.out: ELF 64-bit LSB executable, AMD x86-64, version 1 (SYSV), for GNU/Linux 2.6.9, dynamically linked (uses shared libs), for GNU/Linux 2.6.9, not stripped
尼克，检查预处理器输出的好点。不知何故，std::char_straits 覆盖了 __gnu_cxx::char_straits，并将 int_type 重新定义为 int，而不是像 __gnu_cxx::char_straits 中的 unsigned long。这是非常令人惊讶的！
namespace __gnu_cxx
{
# 61 "/usr/lib/gcc/x86_64-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/char_traits.h" 3
template <class _CharT>
struct _Char_types
{
typedef unsigned long int_type;
typedef std::streampos pos_type;
typedef std::streamoff off_type;
typedef std::mbstate_t state_type;
};
# 86 "/usr/lib/gcc/x86_64-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/char_traits.h" 3
template<typename _CharT>
struct char_traits
{
typedef _CharT char_type;
typedef typename _Char_types<_CharT>::int_type int_type;
typedef typename _Char_types<_CharT>::pos_type pos_type;
typedef typename _Char_types<_CharT>::off_type off_type;
typedef typename _Char_types<_CharT>::state_type state_type;
....
};
namespace std
{
# 224 "/usr/lib/gcc/x86_64-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/char_traits.h" 3
template<class _CharT>
struct char_traits : public __gnu_cxx::char_traits<_CharT>
{ };
template<>
struct char_traits<char>
{
typedef char char_type;
typedef int int_type;
typedef streampos pos_type;
typedef streamoff off_type;
typedef mbstate_t state_type;
...
};
编辑：下面来自 STL 网站http://www.cplusplus.com/reference/string/char_traits/其中 char_traits 专业化使用 int。
typedef INT_T int_type;
Where INT_T is a type that can represent all the valid characters representable by a char_type plus an end-of-file value (eof) which is compatible with iostream class member functions.
For char_traits<char> this is int, and for char_traits<wchar_t> this is wint_t