std :: string有类似CString :: GetBuffer的东西吗？ [英] does std::string have something like CString::GetBuffer?

问题描述

i需要这个，因为Windows的路径函数，比如PathAppend

和PathRemoveFileExt接受一个可写的零终止char *，但我是/>
没有找到std :: string，CString，我通常使用

GetBuffer


LPTSTR CString： ：GetBuffer（int nMinBufLength）

解决方案

On Fri，2008年5月30日03:43:45 -0700，sas写道：

i需要这个，因为windows的路径函数，比如PathAppend和

PathRemoveFileExt接受一个可写零终止char *，但我没有
找到std :: string，用CString，我通常使用GetBuffer for




LPTSTR CString :: GetBuffer（int nMinBufLength）

const char * std :: string :: c_str（）const


-

Lionel B

5月30日，2：23 * pm，Lionel B< m ... @ privacy.netwrote：

On Fri，2008年5月30日03:43:45 -0700，sas写道：

hi，

i需要因为路径的功能，如PathAppend和

PathRemoveFileExt接受一个可写的零终止字符*，但我没有找到bd的字符串，使用CString，我通常使用GetBuffer作为

表示

LPTSTR CString :: GetBuffer（int nMinBufLength）

const char * std :: string :: c_str（）const


-

Lionel B

c_str对我不起作用，因为它返回一个const，我希望是/ b $ b能够将原始的零终止缓冲区传递给一个C函数

更改它，然后告诉字符串对象使用新的

seq进行更新例如：


int a = 5;

CString str;

char * buffer = str.GetBuffer（MAX_PATH）;

sprintf（buffer，" var =％d"，a）;

str.ReleaseBuffer（） ;


str现在是var = 5


带字符串我必须这样做：


int a = 5;

std :: string str;

char buffer [MAX_PATH];

strcpy（buffer，str .c_str（））;

sprintf（缓冲区，var =％d，a）;

str =缓冲区;


i必须为std :: string使用额外的缓冲区

On Fri，2008年5月30日05:41:45 -0700，sas写道：

5月30日，2：23？* pm，Lionel B< m ... @ privacy.netwrote：

> On Fri，2008年5月30日03:43:45 -0700，sas写道：

hi，

i需要因为windows的路径函数，比如PathAppend

和PathRemoveFileExt接受一个可写的零终止char *，但是我没有找到std ::字符串，CString，我通常使用

GetBuffer为

LPTSTR CString :: GetBuffer（int nMinBufLength）

const char * std :: string :: c_str（）const

- Lionel B

^^^^^^^^

（请不要引用sigs）

c_str不适合我，因为它返回一个const，我希望能够将原始的零终止缓冲区传递给改变它的C函数，

然后告诉字符串对象用新序列更新。

不，当然。你不能写到c_str（）一个std :: string。它是

的一部分std :: string的内部并且绝对是只读的而不是

搞砸了;因此const。

例如：


int a = 5;

CString str ;

char * buffer = str.GetBuffer（MAX_PATH）; sprintf（buffer，" var =％d"，a）;

str.ReleaseBuffer（）;


str现在是var = 5

带字符串的
我必须这样做：


int a = 5;

std :: string str ;

char buffer [MAX_PATH];

strcpy（buffer，str.c_str（））;

^^^^^^^^^^^^^^^^^^^^^^^^^^^

这看起来很危险（甚至编译？）并且无论如何都是毫无意义的，因为你后来设置了string = buffer，所以
。把它留下来吧。

sprintf（buffer，" var =％d"，a）;

str = buffer;


i必须为std :: string使用额外的缓冲区

是的，如果你想更新std ::确实如此来自C风格的字符串

字符串。实际上，并不能保证std :: string甚至可以使用char缓冲区实现，而不是
，否则为零终止或

。


-

Lionel B

hi,

i need that because the path functions for windows, like PathAppend
and PathRemoveFileExt accept a writable zero terminated char*, but i
didn''t find that for std::string, with CString, i usually use
GetBuffer for that

LPTSTR CString::GetBuffer( int nMinBufLength )

解决方案

On Fri, 30 May 2008 03:43:45 -0700, sas wrote:

hi,

i need that because the path functions for windows, like PathAppend and
PathRemoveFileExt accept a writable zero terminated char*, but i didn''t
find that for std::string, with CString, i usually use GetBuffer for
that

LPTSTR CString::GetBuffer( int nMinBufLength )

const char* std::string::c_str() const

--
Lionel B

On May 30, 2:23*pm, Lionel B <[e-mail]:

On Fri, 30 May 2008 03:43:45 -0700, sas wrote:

hi,

i need that because the path functions for windows, like PathAppend and
PathRemoveFileExt accept a writable zero terminated char*, but i didn''t
find that for std::string, with CString, i usually use GetBuffer for
that

LPTSTR CString::GetBuffer( int nMinBufLength )

const char* std::string::c_str() const

--
Lionel B

c_str doesn''t work for me, because it returns a const, i want to be
able to pass the raw zero-terminated buffer to a C function that
changes it, then tell the string object to update with the new
sequence.

for example:

int a = 5;
CString str;
char* buffer = str.GetBuffer(MAX_PATH);
sprintf(buffer, "var = %d", a);
str.ReleaseBuffer();

str is now "var = 5"

with string i have to do this:

int a = 5;
std::string str;
char buffer[MAX_PATH];
strcpy(buffer, str.c_str());
sprintf(buffer, "var = %d", a);
str = buffer;

i have to use an additional buffer for std::string

On Fri, 30 May 2008 05:41:45 -0700, sas wrote:

On May 30, 2:23?*pm, Lionel B <[e-mail]:

>On Fri, 30 May 2008 03:43:45 -0700, sas wrote:

hi,

i need that because the path functions for windows, like PathAppend
and PathRemoveFileExt accept a writable zero terminated char*, but i
didn''t find that for std::string, with CString, i usually use
GetBuffer for that

LPTSTR CString::GetBuffer( int nMinBufLength )

const char* std::string::c_str() const

--
Lionel B

^^^^^^^^
(please don''t quote sigs)

c_str doesn''t work for me, because it returns a const, i want to be able
to pass the raw zero-terminated buffer to a C function that changes it,
then tell the string object to update with the new sequence.

No, sure. You can''t "write to the c_str()" of a std::string. It''s part of
the internals of a std::string and is definitely read-only and not to be
messed about with; hence the const.

for example:

int a = 5;
CString str;
char* buffer = str.GetBuffer(MAX_PATH); sprintf(buffer, "var = %d", a);
str.ReleaseBuffer();

str is now "var = 5"

with string i have to do this:

int a = 5;
std::string str;
char buffer[MAX_PATH];
strcpy(buffer, str.c_str());

^^^^^^^^^^^^^^^^^^^^^^^^^^^

This looks dangerous (does it even compile?) and is pointless anyway,
since you later set string = buffer. Just leave it out.

sprintf(buffer, "var = %d", a);
str = buffer;

i have to use an additional buffer for std::string

Yes you do indeed if you want to update a std::string from a C-style
string. In fact there''s no guarantee that a std::string is even
implemented with anything like a char buffer, zero-terminated or
otherwise.

--
Lionel B

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