OTL 4.0, Example 750 (VARCHAR column bound as RAW[XXX] for reading/writing std::strings that have null terminators ('\0') in the middle)

This example demonstrates a technique that allows to read / write std::string values that have null terminators in the middle.

Source Code

#include <iostream>
using namespace std; #include <stdio.h>

#define OTL_STL
#define OTL_ODBC_MSSQL_2008 // Compile OTL 4.0/MSSQL SNAC

#if (defined(__clang__) || defined(__GNUC__)) && \
(defined(OTL_CPP_14_ON) || defined(OTL_CPP_17_ON))
#include <experimental/string_view>
#define OTL_STD_STRING_VIEW_CLASS std::experimental::string_view
#elif defined(_MSC_VER) && (_MSC_VER>=1910) && defined(OTL_CPP_17_ON)
// VC++ 2017 or higher when /std=c++latest is used
#include <string_view>
#define OTL_STD_STRING_VIEW_CLASS std::string_view
#endif
#include <otlv4.h> // include the OTL 4.0 header file
string str_val("123456" "\0" "7890", 11); // std::string with a null terminator in the middle. otl_connect db; // connect object void insert() // insert rows into table { otl_stream o(10, // buffer size "insert into test_tab values(:f1<int>,:f2<raw[30]>)", // SQL statement db // connect object ); for(int i=1;i<=4;++i){ #if defined(OTL_STD_STRING_VIEW_CLASS)
OTL_STD_STRING_VIEW_CLASS str_val_sv(str_val.c_str(),str_val.length());
o<<i<<str_val_sv;
#else
o<<i<<str_val;
#endif
} } void select() { otl_stream i(10, // buffer size "select f1, f2 :#2<raw[30]> "
"from test_tab "
"where f2>=:f2in<raw[30]>", // SELECT statement db // connect object ); // create select stream int f1; string f2; i<<str_val; // assigning :f2in = str_val // SELECT automatically executes when all input variables are // assigned. First portion of output rows is fetched to the buffer while(!i.eof()){ // while not end-of-data i>>f1>>f2; cout<<"f1="<<f1<<", f2="; for(size_t j=0;j<f2.length();++j)
if(f2[j]==0)
cout<<"\\0";
else
cout<<f2[j];
cout<<endl;
} } int main() { otl_connect::otl_initialize(); // initialize the database API environment try{ db.rlogon("scott/tiger@mssql2008"); // connect to the database otl_cursor::direct_exec ( db, "drop table test_tab", otl_exception::disabled // disable OTL exceptions ); // drop table otl_cursor::direct_exec ( db, "create table test_tab(f1 int, f2 varchar(30))" ); // create table insert(); // insert records into table select(); // select records from table } catch(otl_exception& p){ // intercept OTL exceptions cerr<<p.msg<<endl; // print out error message cerr<<p.stm_text<<endl; // print out SQL that caused the error cerr<<p.var_info<<endl; // print out the variable that caused the error } db.logoff(); // disconnect from the database return 0; }

Output

f1=1, f2=123456\07890
f1=2, f2=123456\07890
f1=3, f2=123456\07890
f1=4, f2=123456\07890

Examples Contents Go Home

Copyright 1996-2017, Sergei Kuchin, email: skuchin@gmail.com.

Permission to use, copy, modify and redistribute this document for any purpose is hereby granted without fee, provided that the above copyright notice appear in all copies. THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.