Since wchar_t is 32 bits on Linux, I need to transform wstring to a different type in order to call the ODBC functions. The Windows code, on the other hand, can just use wstrings c_str() function to access the internal representation of the string. My goal is to minimize the code differences between platforms. On Linux, I will create a new class for string16 see earlier post). On Windows, I will just typedef wstring to string16. My hope then is to get the OS specific code down to the Linux implementation of string16, and to have the typedef optimize away the differences.

Here is a simplified version of the code that will be built and run on Windows:

typedef wstring& sqlstring;

void dothing(wstring s){
sqlstring sql(s);
wcout << sql << endl;
}

void doanother(wstring s){
wcout << s << endl;
}

And the result of building and disassembling using g++. Note that the code is the same. Hopefully Windos C++ complier will behave the same.

0000000000400ae0 <_Z9doanotherSbIwSt11char_traitsIwESaIwEE>:
400ae0: 48 83 ec 08 sub $0x8,%rsp
400ae4: 48 89 fe mov %rdi,%rsi
400ae7: bf c0 12 60 00 mov $0x6012c0,%edi
400aec: e8 07 fe ff ff callq 4008f8 <_ZStlsIwSt11char_traitsIwESaIwEERSt13basic_ostreamIT_T0_ES7_R
KSbIS4_S5_T1_E@plt>
400af1: 48 83 c4 08 add $0x8,%rsp
400af5: 48 89 c7 mov %rax,%rdi
400af8: e9 0b fe ff ff jmpq 400908 <_ZSt4endlIwSt11char_traitsIwEERSt13basic_ostreamIT_T0_ES6_@pl
t>
400afd: 90 nop
400afe: 66 90 xchg %ax,%ax

0000000000400b00 <_Z7dothingSbIwSt11char_traitsIwESaIwEE>:
400b00: 48 83 ec 08 sub $0x8,%rsp
400b04: 48 89 fe mov %rdi,%rsi
400b07: bf c0 12 60 00 mov $0x6012c0,%edi
400b0c: e8 e7 fd ff ff callq 4008f8 <_ZStlsIwSt11char_traitsIwESaIwEERSt13basic_ostreamIT_T0_ES7_R
KSbIS4_S5_T1_E@plt>
400b11: 48 83 c4 08 add $0x8,%rsp
400b15: 48 89 c7 mov %rax,%rdi
400b18: e9 eb fd ff ff jmpq 400908 <_ZSt4endlIwSt11char_traitsIwEERSt13basic_ostreamIT_T0_ES6_@pl
t>
400b1d: 90 nop
400b1e: 66 90 xchg %ax,%ax