高效，安全地处理“char *” [英] Efficient, safe handling of "char *"
问题描述
你好，
我写了一个使用Berkeley DB的ISAPI认证模块，
希望它尽可能高效。
ISAPI和BerkeleyDB都使用字符数组（char *）
来传递和接收信息。
我知道C ++字符串应该是正确的
处理字符串但我怀疑转换char *的方式串行
每次我处理它都是昂贵的（分配内存，复制
内容），特别是当很多次我必须转换
字符串返回" char *" （使用c_str（））将其传递给
另一方或返回结果。
是否有已知的类库可以帮助我：
1.创建一个接受char *的对象。 （
以null结尾或使用长度参数）
2.将此字符数组表示为STL容器（提供
迭代器，大部分，但也允许通过迭代器修改数组
）
3.提供原始char *的句柄。参数
没有复制字节数组？
我用Google搜索并且Boost似乎是一个可能的候选人，但它的
文档有点零星，我很难弄明白
什么以及如何使用它。
谢谢，
--V
Vaca Louca写道：
您好，
我编写了一个使用Berkeley DB的ISAPI认证模块，并希望它尽可能高效。
ISAPI和BerkeleyDB都使用字符数组（char *）
传递和接收信息。
我知道C ++字符串应该是正确的字符串。处理字符串的方法，但我怀疑转换char *每次处理它时都很昂贵（分配内存，复制内容），特别是当我多次将
字符串转换回char *时" （使用c_str（））将其向前传递到
另一侧或返回结果。
你不应该直接在任何地方传递c_str（）的返回指针。
是否有已知的类库能以某种方式帮助我：
1.创建一个接受char *的对象。 （
以null结尾或使用长度参数）
2.将此字符数组表示为STL容器（主要提供
迭代器，但也允许修改数组通过迭代器）
3.提供原始char *的句柄。参数
std :: string。 :-)只需将一个字符串对象放在一个名称空间（或全局）作用域中，或者在局部函数作用域中将其作为静态成员或作为类的静态成员。
我将从命名空间范围开始。在这种情况下，您可以将返回的
指针作为const char *传递给c_str（）。
-
Ioannis Vranos
http://www23.brinkster.com/noicys
Ioannis Vranos写道：
我将从命名空间范围开始。在这种情况下，您可以将返回的c_str（）指针作为const char *传递。
....而字符串保持不变。
-
Ioannis Vranos
http://www23.brinkster.com/noicys
Vaca Louca写道：你好，
我编写了一个使用Berkeley DB的ISAPI认证模块，并希望它尽可能高效。
ISAPI和BerkeleyDB都使用字符数组（char *）<传递和接收信息。
我知道C ++字符串应该是正确的。处理字符串的方法，但我怀疑转换char *每次处理它时都很昂贵（分配内存，复制内容），特别是当我多次将
字符串转换回char *时" （使用c_str（））将其向前传递到
另一侧或返回结果。
＃1。你可能是对的 - 但你有没有对代码进行分析，你是否知道这将是一个问题。
＃2。你考虑过懒字符串吗？仅在必要时转换为std :: string
。 ie构造函数在完成任何操作时都会使用const char *和
，而不仅仅是使用char *它将
转换为std :: string。 />
是否有已知的类库可以帮助我以某种方式：
1.创建一个接受char *的对象。 （
以null结尾或使用长度参数）
2.将此字符数组表示为STL容器（主要提供
迭代器，但也允许修改数组通过迭代器）
3.提供原始char *的句柄。参数
没有复制字节数组？
我写了很多这些。
我google了一下，Boost似乎是一个可能的候选人，但它的
文档有点零星的，我正在努力弄清楚
是什么以及如何使用它。
它是什么？
Hello,
I write an ISAPI authentication module which uses Berkeley DB and
want it to be as efficient as possible.
Both ISAPI and BerkeleyDB use arrays of chars (char *)
to pass and receive information.
I know that C++ strings are supposed to be the "right" way to
handle strings but I suspect that converting "char *" to string
every time I deal with it is costly (allocate memory, copy the
content), especially when many times I''ll have to convert the
string back to "char *" (using c_str()) to pass it onward to the
other side or return a result.
Are there known class libraries which can help me somehow:
1. create an object which accepts a "char *" (either
null-terminated or with a length argument)
2. represent this array of chars as an STL container (provide
iterators, mostly, but also allow modification of the array
through the iterators)
3. provides a handle to the original "char *" argument
without copying over the array of bytes?
I googled around and Boost seems like a likely candidate, but its
documentation is a bit sporadic and I''m struggling to figure out
what and how to use it.
Thanks,
--V
Vaca Louca wrote:
Hello,
I write an ISAPI authentication module which uses Berkeley DB and
want it to be as efficient as possible.
Both ISAPI and BerkeleyDB use arrays of chars (char *)
to pass and receive information.
I know that C++ strings are supposed to be the "right" way to
handle strings but I suspect that converting "char *" to string
every time I deal with it is costly (allocate memory, copy the
content), especially when many times I''ll have to convert the
string back to "char *" (using c_str()) to pass it onward to the
other side or return a result.
You shouldn''t pass the returned pointer of c_str() anywhere directly.
Are there known class libraries which can help me somehow:
1. create an object which accepts a "char *" (either
null-terminated or with a length argument)
2. represent this array of chars as an STL container (provide
iterators, mostly, but also allow modification of the array
through the iterators)
3. provides a handle to the original "char *" argument
std::string. :-) Just place a string object in a namespace (or global) scope, or make it
static in a local function scope or as a static member of a class.
I would begin with the namespace scope. And in this case you could pass the returned
pointer of c_str() as a const char * around.
--
Ioannis Vranos
http://www23.brinkster.com/noicys
Ioannis Vranos wrote:
I would begin with the namespace scope. And in this case you could pass
the returned pointer of c_str() as a const char * around.
.... while the string remains unmodified.
--
Ioannis Vranos
http://www23.brinkster.com/noicys
Vaca Louca wrote:Hello,
I write an ISAPI authentication module which uses Berkeley DB and
want it to be as efficient as possible.
Both ISAPI and BerkeleyDB use arrays of chars (char *)
to pass and receive information.
I know that C++ strings are supposed to be the "right" way to
handle strings but I suspect that converting "char *" to string
every time I deal with it is costly (allocate memory, copy the
content), especially when many times I''ll have to convert the
string back to "char *" (using c_str()) to pass it onward to the
other side or return a result.
#1. You may be right - but have you profiled the code and do you "know"
that this will be an issue.
#2. Have you considered a "lazy string" that converts to std::string
only when you have to. i.e. The constructor takes a const char * and
when any operation is done that is more than simply using a char * it is
converted to std::string.
Are there known class libraries which can help me somehow:
1. create an object which accepts a "char *" (either
null-terminated or with a length argument)
2. represent this array of chars as an STL container (provide
iterators, mostly, but also allow modification of the array
through the iterators)
3. provides a handle to the original "char *" argument
without copying over the array of bytes?
I''ve written many of these.
I googled around and Boost seems like a likely candidate, but its
documentation is a bit sporadic and I''m struggling to figure out
what and how to use it.
What is it ?
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