blocks|key|1105177|text|阅读这里的手册：http://curl.haxx.se/libcurl/c/curl_easy_setopt.html我认为您需要多次调用CURL_SETOPT，第一个是您想要处理的URL，第二个类似于：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1105178|curl_easy_setopt(curl,+CURLOPT_WRITEFUNCTION,+function_ptr);|code-block|syntax|javascript|1105179|其中function_ptr与此签名匹配：|1105180|size_t+function(+void+*ptr,+size_t+size,+size_t+nmemb,+void+*stream)|1105181|这里发生的事情是，您指定了一个回调函数，当libcurl有一些输出要从您调用的任何传输中写入时，它将调用该函数。您可以让它自动写入一个文件，或者向它传递一个指向函数的指针，该函数将自己处理输出。使用此函数，您应该能够将各种输出字符串组合成一块，然后在程序中使用它们。|1105182|我不确定您可能需要设置哪些其他选项/哪些其他选项会影响您希望您的应用程序的行为方式，因此请仔细查看该页面。|1105183|entityMap|0|LINK|mutability|MUTABLE|url|http://curl.haxx.se/libcurl/c/curl_easy_setopt.html^0|8|1F|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@$A|Z|B|10|1|11]]|C|$]]|$1|D|3|E|5|F|7|12|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|13|8|@]|9|@]|C|$]]|$1|K|3|L|5|F|7|14|8|@]|9|@]|C|$G|H]]|$1|M|3|N|5|6|7|15|8|@]|9|@]|C|$]]|$1|O|3|P|5|6|7|16|8|@]|9|@]|C|$]]|$1|Q|3|-4|5|6|7|17|8|@]|9|@]|C|$]]]|R|$S|$5|T|U|V|C|$W|X]]]]

From reading the manual here: <a href="http://curl.haxx.se/libcurl/c/curl_easy_setopt.html" rel="noreferrer">http://curl.haxx.se/libcurl/c/curl_easy_setopt.html</a> I think you need several calls to CURL_SETOPT, the first being the URL you want to process, the second being something like:

<pre><code>curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, function_ptr);
</code></pre>

Where function_ptr matches this signature:

<pre><code>size_t function( void *ptr, size_t size, size_t nmemb, void *stream)
</code></pre>

What happens here is you denote a callback function which libcurl will call when it has some output to write from whatever transfer you've invoked. You can get it to automatically write to a file, or pass it a pointer to a function which will handle the output itself. Using this function you should be able to assemble the various output strings into one piece and then use them in your program.

I'm not sure what other options you may have to set / what else affects how you want your app to behave, so have a good look through that page.

blocks|key|1105228|text|您可以使用curl_easy_setopt(curl,+CURLOPT_WRITEFUNCTION,+myfunc);设置回调函数来接收传入的数据块|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1105229|回调将接受一个用户定义的参数，您可以使用curl_easy_setopt(curl,+CURLOPT_WRITEDATA,+p)设置该参数|1105230|下面是一段代码，它将缓冲区struct+string+{*ptr;+len}传递给回调函数，并在每次调用时使用realloc()增加缓冲区。|1105231|#include+<stdio.h>
#include+<stdlib.h>
#include+<string.h>
#include+<curl/curl.h>

struct+string+{
++char+*ptr;
++size_t+len;
};

void+init_string(struct+string+*s)+{
++s->len+=+0;
++s->ptr+=+malloc(s->len%2B1);
++if+(s->ptr+==+NULL)+{
++++fprintf(stderr,+"malloc()+failed\n");
++++exit(EXIT_FAILURE);
++}
++s->ptr[0]+=+'\0';
}

size_t+writefunc(void+*ptr,+size_t+size,+size_t+nmemb,+struct+string+*s)
{
++size_t+new_len+=+s->len+%2B+size*nmemb;
++s->ptr+=+realloc(s->ptr,+new_len%2B1);
++if+(s->ptr+==+NULL)+{
++++fprintf(stderr,+"realloc()+failed\n");
++++exit(EXIT_FAILURE);
++}
++memcpy(s->ptr%2Bs->len,+ptr,+size*nmemb);
++s->ptr[new_len]+=+'\0';
++s->len+=+new_len;

++return+size*nmemb;
}

int+main(void)
{
++CURL+*curl;
++CURLcode+res;

++curl+=+curl_easy_init();
++if(curl)+{
++++struct+string+s;
++++init_string(&s);

++++curl_easy_setopt(curl,+CURLOPT_URL,+"curl.haxx.se");
++++curl_easy_setopt(curl,+CURLOPT_WRITEFUNCTION,+writefunc);
++++curl_easy_setopt(curl,+CURLOPT_WRITEDATA,+&s);
++++res+=+curl_easy_perform(curl);

++++printf("%25s\n",+s.ptr);
++++free(s.ptr);

++++/*+always+cleanup+*/
++++curl_easy_cleanup(curl);
++}
++return+0;
}|code-block|syntax|javascript|1105232|entityMap^0|5|1I|0|K|18|0|D|P|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|T|8|@$9|U|A|V|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|J|3|K|5|L|7|Z|8|@]|D|@]|E|$M|N]]|$1|O|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|P|$]]

You can set a callback function to receive incoming data chunks using <code>curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, myfunc);</code>

The callback will take a user defined argument that you can set using <code>curl_easy_setopt(curl, CURLOPT_WRITEDATA, p)</code>

Here's a snippet of code that passes a buffer <code>struct string {*ptr; len}</code> to the callback function and grows that buffer on each call using realloc().

<pre><code>#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;string.h&gt;
#include &lt;curl/curl.h&gt;

struct string {
 char *ptr;
 size_t len;
};

void init_string(struct string *s) {
 s-&gt;len = 0;
 s-&gt;ptr = malloc(s-&gt;len+1);
 if (s-&gt;ptr == NULL) {
 fprintf(stderr, "malloc() failed\n");
 exit(EXIT_FAILURE);
 }
 s-&gt;ptr[0] = '\0';
}

size_t writefunc(void *ptr, size_t size, size_t nmemb, struct string *s)
{
 size_t new_len = s-&gt;len + size*nmemb;
 s-&gt;ptr = realloc(s-&gt;ptr, new_len+1);
 if (s-&gt;ptr == NULL) {
 fprintf(stderr, "realloc() failed\n");
 exit(EXIT_FAILURE);
 }
 memcpy(s-&gt;ptr+s-&gt;len, ptr, size*nmemb);
 s-&gt;ptr[new_len] = '\0';
 s-&gt;len = new_len;

 return size*nmemb;
}

int main(void)
{
 CURL *curl;
 CURLcode res;

 curl = curl_easy_init();
 if(curl) {
 struct string s;
 init_string(&amp;s);

 curl_easy_setopt(curl, CURLOPT_URL, "curl.haxx.se");
 curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writefunc);
 curl_easy_setopt(curl, CURLOPT_WRITEDATA, &amp;s);
 res = curl_easy_perform(curl);

 printf("%s\n", s.ptr);
 free(s.ptr);

 /* always cleanup */
 curl_easy_cleanup(curl);
 }
 return 0;
}
</code></pre>

blocks|key|1105298|text|下面的答案是使用std::string，而不是以null结尾的字符串，用C%2B%2B的方式来实现。它仍然使用回调函数(没有办法)，但也使用try/catch处理分配错误。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1105299|#include+<iostream>
#include+<string>
#include+<curl/curl.h>

size_t+CurlWrite_CallbackFunc_StdString(void+*contents,+size_t+size,+size_t+nmemb,+std::string+*s)
{
++++size_t+newLength+=+size*nmemb;
++++try
++++{
++++++++s->append((char*)contents,+newLength);
++++}
++++catch(std::bad_alloc+&e)
++++{
++++++++//handle+memory+problem
++++++++return+0;
++++}
++++return+newLength;
}
int+main()
{
++++CURL+*curl;
++++CURLcode+res;

++++curl_global_init(CURL_GLOBAL_DEFAULT);

++++curl+=+curl_easy_init();
++++std::string+s;
++++if(curl)
++++{

++++++++curl_easy_setopt(curl,+CURLOPT_URL,+"curl.haxx.se");

++++++++curl_easy_setopt(curl,+CURLOPT_SSL_VERIFYPEER,+0L);+//only+for+https
++++++++curl_easy_setopt(curl,+CURLOPT_SSL_VERIFYHOST,+0L);+//only+for+https
++++++++curl_easy_setopt(curl,+CURLOPT_WRITEFUNCTION,+CurlWrite_CallbackFunc_StdString);
++++++++curl_easy_setopt(curl,+CURLOPT_WRITEDATA,+&s);
++++++++curl_easy_setopt+(curl,+CURLOPT_VERBOSE,+1L);+//remove+this+to+disable+verbose+output


++++++++/*+Perform+the+request,+res+will+get+the+return+code+*/
++++++++res+=+curl_easy_perform(curl);
++++++++/*+Check+for+errors+*/
++++++++if(res+!=+CURLE_OK)
++++++++{
++++++++++++fprintf(stderr,+"curl_easy_perform()+failed:+%25s\n",
++++++++++++++++++++curl_easy_strerror(res));
++++++++}

++++++++/*+always+cleanup+*/
++++++++curl_easy_cleanup(curl);
++++}

++++std::cout<<s<<std::endl;

++++std::cout<<+"Program+finished!"+<<+std::endl;
}|code-block|syntax|javascript|1105300|entityMap^0|8|B|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

The following answer is the C++ way to do it, with <code>std::string</code>, instead of null-terminated string. It still uses a callback function (there's no way around it), but also handles allocation error using try/catch.

<pre><code>#include &lt;iostream&gt;
#include &lt;string&gt;
#include &lt;curl/curl.h&gt;

size_t CurlWrite_CallbackFunc_StdString(void *contents, size_t size, size_t nmemb, std::string *s)
{
 size_t newLength = size*nmemb;
 try
 {
 s-&gt;append((char*)contents, newLength);
 }
 catch(std::bad_alloc &amp;e)
 {
 //handle memory problem
 return 0;
 }
 return newLength;
}
int main()
{
 CURL *curl;
 CURLcode res;

 curl_global_init(CURL_GLOBAL_DEFAULT);

 curl = curl_easy_init();
 std::string s;
 if(curl)
 {

 curl_easy_setopt(curl, CURLOPT_URL, "curl.haxx.se");

 curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L); //only for https
 curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L); //only for https
 curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, CurlWrite_CallbackFunc_StdString);
 curl_easy_setopt(curl, CURLOPT_WRITEDATA, &amp;s);
 curl_easy_setopt (curl, CURLOPT_VERBOSE, 1L); //remove this to disable verbose output


 /* Perform the request, res will get the return code */
 res = curl_easy_perform(curl);
 /* Check for errors */
 if(res != CURLE_OK)
 {
 fprintf(stderr, "curl_easy_perform() failed: %s\n",
 curl_easy_strerror(res));
 }

 /* always cleanup */
 curl_easy_cleanup(curl);
 }

 std::cout&lt;&lt;s&lt;&lt;std::endl;

 std::cout&lt;&lt; "Program finished!" &lt;&lt; std::endl;
}
</code></pre>

blocks|key|1320263|text|以下是来自alex-jasmin的公认答案的C%2B%2B风格|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1320264|#include+<iostream>
#include+<string>
#include+<curl/curl.h>

size_t+writefunc(void+*ptr,+size_t+size,+size_t+nmemb,+std::string+*s)+
{
++s->append(static_cast<char+*>(ptr),+size*nmemb);
++return+size*nmemb;
}

int+main(void)
{
++CURL+*curl+=+curl_easy_init();
++if+(curl)
++{
++++std::string+s;

++++curl_easy_setopt(curl,+CURLOPT_URL,+"curl.haxx.se");
++++curl_easy_setopt(curl,+CURLOPT_WRITEFUNCTION,+writefunc);
++++curl_easy_setopt(curl,+CURLOPT_WRITEDATA,+&s);

++++CURLcode+res+=+curl_easy_perform(curl);

++++std::cout+<<+s+<<+std::endl;

++++/*+always+cleanup+*/
++++curl_easy_cleanup(curl);
++}
++return+0;
}|code-block|syntax|javascript|1320265|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/users/162407/alex-jasmin^0|5|B|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

Here's a C++ flavor of the accepted answer from <a href="https://stackoverflow.com/users/162407/alex-jasmin">alex-jasmin</a>

<pre class="lang-cpp prettyprint-override"><code>#include &lt;iostream&gt;
#include &lt;string&gt;
#include &lt;curl/curl.h&gt;

size_t writefunc(void *ptr, size_t size, size_t nmemb, std::string *s) 
{
 s-&gt;append(static_cast&lt;char *&gt;(ptr), size*nmemb);
 return size*nmemb;
}

int main(void)
{
 CURL *curl = curl_easy_init();
 if (curl)
 {
 std::string s;

 curl_easy_setopt(curl, CURLOPT_URL, "curl.haxx.se");
 curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writefunc);
 curl_easy_setopt(curl, CURLOPT_WRITEDATA, &amp;s);

 CURLcode res = curl_easy_perform(curl);

 std::cout &lt;&lt; s &lt;&lt; std::endl;

 /* always cleanup */
 curl_easy_cleanup(curl);
 }
 return 0;
}

</code></pre>

I want to store the result of this curl function in a variable, how can I do so?

<pre><code>#include &lt;stdio.h&gt;
#include &lt;curl/curl.h&gt;

int main(void)
{
 CURL *curl;
 CURLcode res;

 curl = curl_easy_init();
 if(curl) {
 curl_easy_setopt(curl, CURLOPT_URL, "curl.haxx.se");
 res = curl_easy_perform(curl);

 /* always cleanup */
 curl_easy_cleanup(curl);
 }
 return 0;
}
</code></pre>

thanks, I solved it like this:

<pre><code>#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;curl/curl.h&gt;

function_pt(void *ptr, size_t size, size_t nmemb, void *stream){
 printf("%d", atoi(ptr));
}

int main(void)
{
 CURL *curl;
 curl = curl_easy_init();
 if(curl) {
 curl_easy_setopt(curl, CURLOPT_URL, "curl.haxx.se");
 curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, function_pt);
 curl_easy_perform(curl);
 curl_easy_cleanup(curl);
 }
 system("pause");
 return 0;
}
</code></pre>

C libcurl get output into a string

我想把这个curl函数的结果存储在一个变量中，我该怎么做呢？#include <stdio.h>#include <curl/curl.h>int main(void){ CURL *curl; CURLcode res; curl = curl_easy_init(); if(curl) { curl_...

问C libcurl get输出为字符串
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