LibCurl CURLOPT_URL not accepting string? C++
c++, libcurl, syntax-error
Solution
The parameter passed to `curl_easy_setopt` for `CURLOPT_URL` needs to be a `char *` instead of a `std::string`. You can get a `const char *` from a `std::string` by calling its `c_str` member function:
std::string url = "http://foo.com/foo.asp?name=" + *i;
curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
For anyone who ends up here in the future, take a look at the curl manual if you haven't already. There's also an online book.
The documentation for curl_easy_setopt says you need to read about a specific option to know what parameter type to use.
All options are set with an option followed by a parameter. That parameter can be a long, a function pointer, an object pointer or a curl_off_t, depending on what the specific option expects. Read this manual carefully as bad input values may cause libcurl to behave badly!
The documentation for CURLOPT_URL says exactly what the parameter type needs to be.
Pass in a pointer to the URL to work with. The parameter should be a char * to a zero terminated string which must be URL-encoded in the following format:
scheme://host:port/path
Problem
So basically what I want to do is use libcurl to fetch slightly different urls, e.g.: ``` http://foo.com/foo.asp?name=*NAMEHERE* ``` What I would like to do is iterate through a vector of names and get each one, e.g.: ``` http://foo.com/foo.asp?name=James ``` Then ``` http://foo.com/foo.asp?name=Andrew ``` And so on. However, when I try doing this: ``` int foo (){ CURL *curl; CURLcode success; char errbuf[CURL_ERROR_SIZE]; int m_timeout = 15; if ((curl = curl_easy_init()) == NULL) { perror("curl_easy_init"); return 1; } std::vector<std::string> names; names.push_back("James"); names.push_back("Andrew"); for (std::vector<std::string>::const_iterator i = names.begin(); i != names.end(); ++i){ curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, errbuf); curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L); curl_easy_setopt(curl, CURLOPT_TIMEOUT, long(m_timeout)); curl_easy_setopt(curl, CURLOPT_URL, "http://foo.com/foo.asp?name=" + *i); curl_easy_setopt(curl, CURLOPT_COOKIEFILE, "cookies.txt"); curl_easy_setopt(curl, CURLOPT_COOKIEJAR, "cookies.txt"); curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L); curl_easy_setopt(curl, CURLOPT_AUTOREFERER, 1L); } if ((success = curl_easy_perform(curl)) != 0) { fprintf(stderr, "%s: %s\n", "curl_easy_perform", errbuf); return 1; } curl_easy_cleanup(curl); return 0; } ``` It gives me an error: Cannot pass object of non-trivial type 'std::__1::basic_string<char>' through variadic function; call will abort at runtime On this line: ``` curl_easy_setopt(curl, CURLOPT_URL, "http://foo.com/foo.asp?name=" + *i); ``` because of the `+ *i`. Is what I want to do possible? Is there a solution? EDIT: Thanks for the answer, but for some reason, when I run this it only gets the website with the last string in the vector, and it ignores the other ones. In my case, it skips `James` and goes straight to `Andrew`. Why does that happen?