error: invalid operands of types ‘const char*’ and ‘const char [4]’ to binary ‘operator+’

[Mathias Panzenböck]

I would not build the string like that at all. Also I don't think a + operator for int and 
std::string is defined (which would be needed for the track).

Use e.g.:

std::stringstream ss;
ss << "INSERT INTO SongList (track, name, genre, artist, album, time, uri) values (" <<
	tag->track() << ", '" << tag->title() << "', '" << tag->genre() + "', '" <<
	tag->artist() << "', '" << tag->album() << "', '" << minutes << ":" <<
	seconds << "', '" << *iter << "');";
std::string insert = ss.str();

But then you should not build an SQL query like that anyway because of possible injection attacks. 
Or just plain buggy behaviour (what if the title or artist contains a ' character? it's not that 
uncommon). Isn't there an API somethink like this for the SQL lib you use?

Query insert("INSERT INTO SongList (track, name, genre, artist, album, time, uri) "
              "values (?, ?, ?, ?, ?, ?, ?);");

insert
	.addParameter(tag->track())
	.addParameter(tag->title())
	.addParameter(tag->genre())
	.addParameter(tag->artist())
	.addParameter(tag->album())
	.addParameter(minutes)
	.addParameter(*iter);

connection.execute(insert);


	-panzi

On 07/01/2011 02:26 AM, Phong Cao wrote:
> Hello everybody,
>
> I am trying to use TagLib to extract tags from a stream and store it in a std::string. Here is the
> function I used:
>
> void TopWin::insert_tag_on_db(std::vector<std::string> &filenames) {
>    for (std::vector<std::string>::iterator iter = filenames.begin(); iter != filenames.end(); ++iter) {
>      TagLib::FileRef file((*iter).c_str());
>      if (!file.isNull() && file.tag()) {
>        TagLib::Tag *tag = file.tag();
>        TagLib::AudioProperties *properties = file.audioProperties();
>        int seconds = properties->length() % 60;
>        int minutes = (properties->length() - seconds) / 60;
>        //error occurs here
>        std::string insert = "INSERT INTO SongList (track, name, genre, artist, album, time, uri)
> values (" + tag->track() + ", '" + tag->title() + "', '" + tag->genre() + "', '" + tag->artist() +
> "', '" + tag->album() + "', '" + minutes + ":" + seconds + "', '" + *iter + "');";
>      }
>    }
> }
>
> However, the program was not compiled. g++ reported an error:
>
> /home/phongcao/dingo/topwin.cc:16: error: invalid operands of types ‘const char*’ and ‘const char
> [4]’ to binary ‘operator+’
>
> I have read the TagLib documentation and it said that the TagLib's return type is TagLib::String.
> What I do not understand here is whether TagLib::String is similar to std::string or char*? If it is
> similar to std::string then what is the source of the above error?
>
> I guess the source of the error is that I was trying to concatenate tag->title(), tag->track(),
> etc... (which may have types char*, since I do not know TagLib::String is a CString or a
> std::string) to a string literal. Can you guys suggest a solution to fix this error?
>
>
> Thank you for reading my message! Have a good day!
>
>
> Best regards,
>
> --
> Phong V. Cao
> phngcv at gmail.com <mailto:phngcv at gmail.com>
> caoph at rider.edu <mailto:caoph at rider.edu>
>
>
>
>
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