C++ 不能传递非 POD 类型的对象
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C++ cannot pass objects of non-POD type
提问by ash-breeze
This is my code:
这是我的代码：
#include <iostream>
#include <fstream>
#include <cstdlib>
#include <stdio.h>
#include <curl/curl.h>
using namespace std;
int main ()
{
ifstream llfile;
llfile.open("C:/log.txt");
if(!llfile.is_open()){
exit(EXIT_FAILURE);
}
string word;
llfile >> word;
llfile.close();
string url = "http://example/auth.php?ll=" + word;
CURL *curl;
CURLcode res;
curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, url);
res = curl_easy_perform(curl);
/* always cleanup */
curl_easy_cleanup(curl);
}
return 0;
}
This is my error when compiling:
这是我编译时的错误：
main.cpp|29|warning: cannot pass objects of non-POD type
'struct std::string'through'...'; call will abort at runtime
的main.cpp | 29 |警告：不能通过非POD类型的对象
'struct std::string'通过'...'; 调用将在运行时中止
回答by David Rodríguez - dribeas
The problem you have is that variable argument functions do not work on non-POD types, including std::string. That is a limiation of the system and cannot be modified. What you can, on the other hand, is change your code to pass a POD type (in particular a pointer to a nul terminated character array):
您遇到的问题是可变参数函数不适用于非 POD 类型，包括std::string. 这是系统的限制，无法修改。另一方面，您可以更改代码以传递 POD 类型（特别是指向以 nul 结尾的字符数组的指针）：
curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
回答by ildjarn
As the warning indicates, std::stringis not a POD-type, and POD-types are required when calling variadic-argument functions (i.e., functions with an ...argument).
如警告所示，std::string不是 POD 类型，并且在调用可变参数函数（即带有参数的函数）时需要 POD 类型...。
However, char const*is appropriate here; change
然而，char const*这里是合适的；改变
curl_easy_setopt(curl, CURLOPT_URL, url);
to
到
curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
