I have a simple table called mytable2 with only one column, name as varchar2(20). I now have a list of names stored as vector of std::string to be inserted into the table. I want to use executeArrayUpdate, so I must do the setDataBuffer first. However, as I could see, people always use char[][20] to set databuffer.
This leaves me a big headache, since I have two issues here, first is to convert from vector to array, second is to convert the string to char.
1st, I tired to use vector of char[20], and this doesn't compile. Googled and they say that vector can't take char[], so I changed my vector of std::string to vector of char*.
2nd, I tried to turn the vector to arrray by using "void* p=&names[0]", as some people say this way we can use vectors just as array.
I used stmt->setDataBuffer(1,mystring,OCCI_SQLT_STR,20,NULL), and the program compiled and executed alright, but when I "select name from mytable2", it showed only some strange charaters.
Anyone has had a similiar issue before? what should I do?
My code is simple as below:
count=2;
vector<char*> mystring;
for(int i=0;i<count;i++)
{
char my[20];
strcpy_s(my,"Michael");
mystring.insert(mystring.end(),my);
}
stmt->setDataBuffer(1,&mystring[0],OCCI_SQLT_STR,20,NULL);
stmt->setBatchErrorMode (true);
stmt->executeArrayUpdate(count);
You'd need to dynamically create the char array you're putting into the vector for it to have a chance of working correctly.
I have not used OCCI, but if I had to use API that asked for char[][20], I would give it char[][20]
If you have your existing data in vector, why not just copy it across into the 2D char array? Eg.
// intialise vector with nonsense
unsigned int const VEC_SIZE = 2 ;
vector<string> v;
for (unsigned int i = 0; i < VEC_SIZE; ++i) {
stringstream s;
s << "Jon Paul " << i << endl;
v.push_back ( s.str() ) ;
}
// create the required 2D char array
unsigned int const STR_LEN = 20 ;
char c [VEC_SIZE][STR_LEN];
// copy the data from the vector of strings to the 2D char array
for (unsigned int i = 0; i < VEC_SIZE; ++i) {
string s = v[i].substr(0,STR_LEN);
char const * const cc = s.c_str();
unsigned int j = 0;
for (; j < STR_LEN && j < s.size(); ++j) {
c[i][j] = cc[j];
}
c[i][ j==STR_LEN ? 20 : j ] = 0; // write NULL character
}
I take it you've simplified your example to be a fixed size vector, so my response is going to be simplified to, with the thorny issue of dynamic allocation of 2D arrays left as an exercise for the reader...