char *curl_easy_escape( CURL *curl, char *url, int length );
This function converts the given input string to an URL encoded string and
returns that as a new allocated string. All input characters that are not a-z,
A-Z or 0-9 are converted to their "URL escaped" version (%NN where NN is a
two-digit hexadecimal number).
If the length argument is set to 0 (zero), curl_easy_escape(3)
uses strlen() on the input url to find out the size.
You must curl_free(3) the returned string when you're done with it.
Added in 7.15.4 and replaces the old curl_escape(3) function.
A pointer to a zero terminated string or NULL if it failed.