c++ - Problem when converting char* to string -

when convert char* string gives bad memory allocation error in 'new.cpp' . used following method convert char* called 'strdata' , 'strorg' string.

   const char* strdata = dt.data();    int length2 = dt.length();    string s1(strdata); 

first time work without problem. in second convertion gives above error. when swap 2 conversion in order, give error in second conversion regardless of char* converting. whole code shown in following.

    mysqlpp::query query = conn.query("select data,origin image id =2");     mysqlpp::usequeryresult res = query.use();     mysqlpp::row eee= res.fetch_row();     mysqlpp::row::reference dt = eee.at(0);     mysqlpp::row::reference org = eee.at(1);      const char* strdata = dt.data();     int length2 = dt.length();     string s1(strdata);     istringstream is1(s1);       char * imgdata =  new char;     is1.read(reinterpret_cast<char *> (imgdata), length2);     delete [] strdata;      const char* strorg = org.data();     int length3 = org.length();     string s2(strorg);     istringstream is2(s2);       char * imgorg =  new char;     is2.read(reinterpret_cast<char *> (imgorg), length3);     delete [] strorg; 

this error comes from

    void *__crtdecl operator new(size_t size) _throw1(_std bad_alloc)     {            void *p;     while ((p = malloc(size)) == 0)             if (_callnewh(size) == 0)             {       // report no memory             static const std::bad_alloc nomem;             _raise(nomem);             }      return (p);     } 

please me solve problem. urgent

instead of

char * imgdata = new char; is1.read(reinterpret_cast<char *> (imgdata), length2); 

try

char * imgdata = new char[length2]; is1.read(reinterpret_cast<char *> (imgdata), length2); 

when read data istringstream using read, buffer provide must have enough space hold results!

if call new char; space 1 char. use new char[n]; space n.