Implementing cdbpp library for string values

Question

I am trying to implement the cdbpp library from chokkan. I am facing some problems when I was trying to implement the same for values with data type of strings.

The original code and documentation can be found here: http://www.chokkan.org/software/cdbpp/ and the git source code is here: https://github.com/chokkan/cdbpp

This is what I have so far: In the sample.cpp (from where i am calling the main function), I modified the build() function:

bool build()
{
// Open a database file for writing (with binary mode).
std::ofstream ofs(DBNAME, std::ios_base::binary);
if (ofs.fail()) {
    std::cerr << "ERROR: Failed to open a database file." << std::endl;
    return false;
}

try {
    // Create an instance of CDB++ writer.
    cdbpp::builder dbw(ofs);

    // Insert key/value pairs to the CDB++ writer.
    for (int i = 1;i < N;++i) {
        std::string key = int2str(i);
        const char* val = "foobar";  //string value here
        dbw.put(key.c_str(), key.length(), &val, sizeof(i));
    }


} catch (const cdbpp::builder_exception& e) {
    // Abort if something went wrong...
    std::cerr << "ERROR: " << e.what() << std::endl;
    return false;
}

return true;
}

and in cdbpp.h file, i modified the put() function as :

void put(const key_t *key, size_t ksize, const value_t *value, size_t vsize)
{
    // Write out the current record.
    std::string temp2 = *value;
    const char* temp = temp2.c_str();
    write_uint32((uint32_t)ksize);
    m_os.write(reinterpret_cast<const char *>(key), ksize);
    write_uint32((uint32_t)vsize);
    m_os.write(reinterpret_cast<const char *>(temp), vsize);
    // Compute the hash value and choose a hash table.
    uint32_t hv = hash_function()(static_cast<const void *>(key), ksize);
    hashtable& ht = m_ht[hv % NUM_TABLES];

    // Store the hash value and offset to the hash table.
    ht.push_back(bucket(hv, m_cur));

    // Increment the current position.
    m_cur += sizeof(uint32_t) + ksize + sizeof(uint32_t) + vsize;

}

Now the I get the correct value if the string is less than or equal to 3 characters(eg: foo will return foo). If it is greater than 3 it gives me the correct string up to 3 characters then garbage value(eg. foobar gives me foo�`)

I am a little new to c++ and I would appreciate any help you could give me.

Answer 1

(moving possible answer in comment to real answer)

vsize as passed into put is the size of an integer when it should be the length of the value string.