错误：无法转换“std::string”到“char*”在初始化中
我有Python脚本，可以从网页下载汇率，我想从中制作C++程序，这是我到目前为止所拥有的：
include iostream
include time.h
include stdio.h
include curl/curl.h
include curl/easy.h
include string
define CURL_STATICLIB
using namespace std;
void dat(string &d){
time_t rawtime;
struct tm * timeinfo;
char datum[80];
time ( &rawtime );
timeinfo=localtime(&rawtime);
strftime(datum,80,"%d%m%y",timeinfo);
d=datum;
}
size_t write_data(void *ptr, size_t size, size_t nmemb, FILE *stream) {
size_t written;
written = fwrite(ptr, size, nmemb, stream);
return written;
}
int main()
{
string f;
dat(f);
string l1="http://www.hnb.hr/tecajn/f";
string l2=".dat";
string linkz=l1+f+l2;
cout << linkz;
CURL *curl;
FILE *fp;
CURLcode res;
char *url = linkz;
char outfilename[FILENAME_MAX] = "/home/tomi/data.txt";
curl = curl_easy_init();
if (curl) {
fp = fopen(outfilename,"wb");
curl_easy_setopt(curl, CURLOPT_URL, url);
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);
res = curl_easy_perform(curl);
curl_easy_cleanup(curl);
fclose(fp);
return 0;
}
当我尝试编译时，它给了我这个错误，我发现使用了下载txt的算法，所以我希望它是正确的
i have python script that download exchange rates from web page, and i want make c++ program from that, here is what i have so far:
include iostream
include time.h
include stdio.h
include curl/curl.h
include curl/easy.h
include string
define CURL_STATICLIB
using namespace std;
void dat(string &d){
time_t rawtime;
struct tm * timeinfo;
char datum[80];
time ( &rawtime );
timeinfo=localtime(&rawtime);
strftime(datum,80,"%d%m%y",timeinfo);
d=datum;
}
size_t write_data(void *ptr, size_t size, size_t nmemb, FILE *stream) {
size_t written;
written = fwrite(ptr, size, nmemb, stream);
return written;
}
int main()
{
string f;
dat(f);
string l1="http://www.hnb.hr/tecajn/f";
string l2=".dat";
string linkz=l1+f+l2;
cout << linkz;
CURL *curl;
FILE *fp;
CURLcode res;
char *url = linkz;
char outfilename[FILENAME_MAX] = "/home/tomi/data.txt";
curl = curl_easy_init();
if (curl) {
fp = fopen(outfilename,"wb");
curl_easy_setopt(curl, CURLOPT_URL, url);
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);
res = curl_easy_perform(curl);
curl_easy_cleanup(curl);
fclose(fp);
return 0;
}
it give me this error when i try to compile, i found used algorythm for download txt, so i hope it is correct
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如果您指出了出现错误的行，我就不必跟踪它：
您可以使用
c_str()来获取指向 const 字符的指针细绳。这样就可以了：您可以在
setopt调用中使用同一行，或者将url也设置为std::string。If you'd have pointed out the line where you got the error, I wouldn't have had to track it down to:
You can use
c_str()to get a pointer to the const characters in the string. So this will do:You could have that very same line in the
setoptcall, or haveurlbe anstd::stringas well.char *url = linkz;应该是const char* url = linkz.c_str();假设您出于 API 原因确实需要 C 样式字符串。char *url = linkz;should beconst char* url = linkz.c_str();assuming you really need a C-style string for API reasons.问题出在这一行：
“links”是一个 std::string，但“url”是一个 char *。尝试使用字符串的 c_str 方法来获取您需要的内容，如下所示：
The problem is in this line:
"links" is an std::string, but"url" is a char *. Try using the c_str method of string to get what you need like so: