_vsnprintf崩溃

[flamkuavos]

#include <string>
using namespace std;
#include <stdarg.h>

inline std::string mystr_fmt(const char* fmt, ...)
{
	va_list argptr;
	va_start(argptr, fmt);
	int rst_size = _vsnprintf(NULL, 0, fmt, argptr) + 2; //运行到这里要崩溃，咋回事？
	char* rst_tmp = new char[rst_size];
	_vsnprintf(rst_tmp, rst_size, fmt, argptr);
	string rst(rst_tmp);
	delete[] rst_tmp;
	rst_tmp = NULL;
	va_end(argptr);
	return rst;
}

void main()
{
	mystr_fmt("%d", 2);
}

此程序可以运行，VC6

[gohay1]

vsnprintf,_vsnprintf, and _vsnwprintf return the number of characters written if the number of characters to write is less than or equal to count; if the number of characters to write is greater than count, these functions return -1 indicating that output has been truncated. The return value does not include the terminating null, if one is written. If buffer or format is NULL, or if count is less than or equal to zero, these functions invoke the invalid parameter handler, as described in Parameter Validation. If execution is allowed to continue, these functions return -1 and set errno to EINVAL.

[JiMoKuangXiangQu]

#include <string> 
using namespace std; 
#include <stdarg.h>   

inline std::string mystr_fmt(const char* fmt, ...) 
{     
	va_list argptr;     
	va_start(argptr, fmt);     
	int rst_size = _vsnprintf(NULL, 0, fmt, argptr) + 2; //运行到这里要崩溃，咋回事？     
	char* rst_tmp = new char[rst_size];     
	_vsnprintf(rst_tmp, rst_size, fmt, argptr);     
	string rst(rst_tmp);     
	delete[] rst_tmp;     
	rst_tmp = NULL;     
	va_end(argptr);     
	return rst; 
}   

void main() 
{     
	mystr_fmt("%d", 2); 
	return;
}

用vs2008跑了下,程序可以运行.

[sduxiaoxiang]

远离VC6吧

[swordtan]

引用 1 楼 gohay1 的回复:

vsnprintf,_vsnprintf, and _vsnwprintf return the number of characters written if the number of characters to write is less than or equal to count; if the number of characters to write is ……

++ http://msdn.microsoft.com/en-us/library/1kt27hek.aspx http://msdn.microsoft.com/en-us/library/ksazx244.aspx