Stable_sort сортировка вектора по последнему символу

void setText()
{
    string number;
    FILE *file;
    char* file_name = "file.txt";
    file = fopen( file_name, "w" ); 
    fputs( "12 41 55 74 95 67 83 99 17", file );
    fclose( file );
}
string getText()
{
    FILE *file;
    char* file_name = "file.txt";
    char load_string[99] = "none";
    file = fopen( file_name, "r" );
    if( file != 0 )
    {
        fgets( load_string, 99 , file );
    }
    else
    {
        cout << "File not found !!!" << endl;
    }
        fclose(file);
    return load_string;
}
 
void main()
{
    string s;
    setText();
    s=getText();
    char delitel =' ';
    ostream_iterator< int >  output(cout," ");
    ostream_iterator< string >  outputString(cout,"");
    //-----
    vector<int> V;
    string temp="";
    for(int i=0;i<s.length();i++){
        if(s[i]==' '||s[i]=='\0'){V.push_back(atoi(temp.c_str()));temp="";}
    temp+=s[i];
    }
    
 
    cout<<"Vector is:\n";
    std::copy(V.begin(),V.end(),output);
 
    stable_sort(V.begin(),V.end());
 
        cout<<"Vector is:\n";
    std::copy(V.begin(),V.end(),output);
    cin.get();
 
 
}

bool compare_as_ints (int i,int j)
{
  char buff[32];
  sprintf(buff,"%d",i);
  string s1 = string(buff);
 
  sprintf(buff,"%d",j);
  string s2 = string(buff);
  
  return ((s1[1])<(s2[1]));
}