Filling a string buffer when using Ocilib

问题

I'm using Ocilib to perform a bulk insert on a Oracle database but I'm having some trouble while filling a string buffer.

The documentation says:

For string/RAW arrays, the input array MUST BE a contiguous block of data and not an array of pointers. So to bind an array of 10 elements for a varchar2(30) column, binded variable must be a like array[10][31]

And a sample proceeds to fill a buffer like this:

...
char tab_str[1000][21];
...
OCI_BindArrayOfStrings(st, ":s", (char*) tab_str, 20, 0);
...

for(i=0;i<1000;i++)
{
    sprintf(tab_str[i],"Name %d",i+1);
}
...

I'm trying to fill the string buffer while looping through a std::vector of MyClass. MyClass has a std::string member.

I'm trying to use the std::string::copy method to copy over the string contents to the buffer. But I don't know exactly how to index the buffer to do it.

...
OCI_BindArrayOfStrings(st, ":f2", NULL, VCHAR_SIZE, 0);
char** vc_buffer = (char**)OCI_BindGetData(OCI_GetBind(st, 2));
...
int i = 0;
for(vector<MyClass>::const_iterator it = myVec.begin(); it != myVec.end(); ++it)
{
    /* 1st try */ it->m_string.copy((vc_buffer + (i * VCHAR_SIZE)), VCHAR_SIZE);
    /* 2nd try */ it->m_string.copy(vc_buffer[i], VCHAR_SIZE);
    ++i;
    ...
}
...

The first way gives me buggy data in the database. The second makes me hit a null pointer.

What I'm doing wrong?

PS:

The second approach, along the approach proposed by Alessandro Vergani below, results in null strings inserted. The first approach gives this (somewhat bizarre) result:

The gvim window shows what it's supposed to look like, the apex screen shows what ends up in the database.

回答1:

(Try:

std::vector<char> tab_str(myVec.size() * (VCHAR_SIZE + 1));
...
OCI_BindArrayOfStrings(st, ":s", &tab_str[0], VCHAR_SIZE, 0);
...
int offset = 0;
for(vector<MyClass>::const_iterator it = myVec.begin(); it != myVec.end(); ++it, offset += VCHAR_SIZE)
{
    it->m_string.copy(&tab_str[offset], VCHAR_SIZE);
    ...        
}
...

I'm not sure you need to add the null terminator: if not, remove the -1 from the copy and remove the second line.

来源：https://stackoverflow.com/questions/4887792/filling-a-string-buffer-when-using-ocilib

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c++

oci