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cUrl/libcurl not working. Multiple unresolved externals

ExSanity (82)
Hello, I am attempting to use cURL to send a POST request to my web server, yet I am running into many many many issues. First, it took me a minute to figure out what I though I needed to do. I moved the CURL folder from the 'Include' folder into my MSVC project and I compiled libcurl moved it into my project. I have define CURL_STATICLIB in preprocessor.

From a cURL example so it should work.
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#include <conio.h>
#include "stdafx.h"
#include "curl\curl.h"
#include <Windows.h>
#include <WinSock2.h>
#pragma comment (lib, "ws2_32.lib")
#pragma comment(lib, "libcurl.lib")
int main()
{
	CURL *cUrl;
	CURLcode res;

	/* Initialize all things with cUrl */
	curl_global_init(CURL_GLOBAL_ALL);
	/* Get cUrl Hangle */
	cUrl = curl_easy_init();
	if (cUrl)
	{
		/* Set URL for us to $POST to */
		curl_easy_setopt(cUrl, CURLOPT_URL, "http://jimmyonhentai.x10host.com/");
		curl_easy_setopt(cUrl, CURLOPT_POSTFIELDS, "name=Hello&extra=, World");
		/* Preform the request. */
		res = curl_easy_perform(cUrl);
		if (res != CURLE_OK)
			printf("Whoops! Failed to perform! %s\n", curl_easy_strerror(res));
		curl_easy_cleanup(cUrl);
	}
	curl_global_cleanup();
	printf("Done!");
	getch();
    return 0;
}


Errors:
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Severity	Code	Description	Project	File	Line	Suppression State
Error	LNK1120	16 unresolved externals	curltest	c:\users\justin\documents\visual studio 2017\Projects\curltest\Debug\curltest.exe	1	
Error	LNK2019	unresolved external symbol __imp__ber_free referenced in function _Curl_ldap	curltest	c:\Users\Justin\documents\visual studio 2017\Projects\curltest\curltest\libcurl.lib(ldap.obj)	1	
Error	LNK2019	unresolved external symbol __imp__ldap_bind_s referenced in function _ldap_win_bind	curltest	c:\Users\Justin\documents\visual studio 2017\Projects\curltest\curltest\libcurl.lib(ldap.obj)	1	
Error	LNK2019	unresolved external symbol __imp__ldap_err2string referenced in function _Curl_ldap	curltest	c:\Users\Justin\documents\visual studio 2017\Projects\curltest\curltest\libcurl.lib(ldap.obj)	1	
Error	LNK2019	unresolved external symbol __imp__ldap_first_attribute referenced in function _Curl_ldap	curltest	c:\Users\Justin\documents\visual studio 2017\Projects\curltest\curltest\libcurl.lib(ldap.obj)	1	
Error	LNK2019	unresolved external symbol __imp__ldap_first_entry referenced in function _Curl_ldap	curltest	c:\Users\Justin\documents\visual studio 2017\Projects\curltest\curltest\libcurl.lib(ldap.obj)	1	
Error	LNK2019	unresolved external symbol __imp__ldap_get_dn referenced in function _Curl_ldap	curltest	c:\Users\Justin\documents\visual studio 2017\Projects\curltest\curltest\libcurl.lib(ldap.obj)	1	
Error	LNK2019	unresolved external symbol __imp__ldap_get_values_len referenced in function _Curl_ldap	curltest	c:\Users\Justin\documents\visual studio 2017\Projects\curltest\curltest\libcurl.lib(ldap.obj)	1	
Error	LNK2019	unresolved external symbol __imp__ldap_init referenced in function _Curl_ldap	curltest	c:\Users\Justin\documents\visual studio 2017\Projects\curltest\curltest\libcurl.lib(ldap.obj)	1	
Error	LNK2019	unresolved external symbol __imp__ldap_memfree referenced in function _Curl_ldap	curltest	c:\Users\Justin\documents\visual studio 2017\Projects\curltest\curltest\libcurl.lib(ldap.obj)	1	
Error	LNK2019	unresolved external symbol __imp__ldap_msgfree referenced in function _Curl_ldap	curltest	c:\Users\Justin\documents\visual studio 2017\Projects\curltest\curltest\libcurl.lib(ldap.obj)	1	
Error	LNK2019	unresolved external symbol __imp__ldap_next_attribute referenced in function _Curl_ldap	curltest	c:\Users\Justin\documents\visual studio 2017\Projects\curltest\curltest\libcurl.lib(ldap.obj)	1	
Error	LNK2019	unresolved external symbol __imp__ldap_next_entry referenced in function _Curl_ldap	curltest	c:\Users\Justin\documents\visual studio 2017\Projects\curltest\curltest\libcurl.lib(ldap.obj)	1	
Error	LNK2019	unresolved external symbol __imp__ldap_search_s referenced in function _Curl_ldap	curltest	c:\Users\Justin\documents\visual studio 2017\Projects\curltest\curltest\libcurl.lib(ldap.obj)	1	
Error	LNK2019	unresolved external symbol __imp__ldap_set_option referenced in function _Curl_ldap	curltest	c:\Users\Justin\documents\visual studio 2017\Projects\curltest\curltest\libcurl.lib(ldap.obj)	1	
Error	LNK2019	unresolved external symbol __imp__ldap_unbind_s referenced in function _Curl_ldap	curltest	c:\Users\Justin\documents\visual studio 2017\Projects\curltest\curltest\libcurl.lib(ldap.obj)	1	
Error	LNK2019	unresolved external symbol __imp__ldap_value_free_len referenced in function _Curl_ldap	curltest	c:\Users\Justin\documents\visual studio 2017\Projects\curltest\curltest\libcurl.lib(ldap.obj)	1
JLBorges (13770)
These unresolved externals are for LDAP functions.

Try adding this: #pragma comment ( lib, "wldap32.lib" ) // implicitly link to the windows ldap library

Alternatively, since you do not appear to need LDAP functionality, you can build libCURL without LDAP support.
Preprocessor: in addition to defining CURL_STATICLIB also define CURL_DISABLE_LDAP
Last edited on
ExSanity (82)
Including the lib worked fine! thanks man :)

Edit:
Sorry to ask two questions in one thread but is there any way to store the return from the web server? I know preform() will print what the web server echoes but can I store what it echoes to and strcmp() it?
Last edited on
JLBorges (13770)
Provide your own callback function which consumes the received data.
https://curl.haxx.se/libcurl/c/CURLOPT_WRITEFUNCTION.html
https://curl.haxx.se/libcurl/c/CURLOPT_WRITEDATA.html

For instance:
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// consume the data received by curl (append to the string)
static int append_to_string( char* recd_data, size_t size, size_t nmemb, std::string* ptr_string )
{
    const std::size_t nbytes = size * nmemb ;

    if( ptr_string && recd_data && nbytes )
    {
        ptr_string->append( recd_data, nbytes ) ;
        return nbytes ;
    }

    else return 0 ;
}


And then: 
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std::string recd_string ; // string to hold the bytes returned by the server
std::string* ptr_string = std::addressof(recd_string) ; // address of the string 

curl_easy_setopt( curl_handle, CURLOPT_WRITEFUNCTION, append_to_string ); // set the write callback function
curl_easy_setopt( curl_handle, CURLOPT_WRITEDATA, ptr_string ); // to which this pointer is to be passed as the last argument
ExSanity (82)
I tried that
(With this code)
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std::string recd_string; // string to hold the bytes returned by the server
std::string* ptr_string = std::addressof(recd_string); // address of the string 
static int append_to_string(char* recd_data, size_t size, size_t nmemb, std::string* ptr_string)
{
	const std::size_t nbytes = size * nmemb;

	if (ptr_string && recd_data && nbytes)
	{
		ptr_string->append(recd_data, nbytes);
		return nbytes;
	}

	else return 0;
}
int main()
{
	CURL *cUrl;
	CURLcode res;

	/* Initialize all things with cUrl */
	curl_global_init(CURL_GLOBAL_ALL);
	/* Get cUrl Hangle */
	cUrl = curl_easy_init();
	if (cUrl)
	{
		/* Set URL for us to $POST to */
		curl_easy_setopt(cUrl, CURLOPT_URL, "http://jimmyonhentai.x10host.com/script.php");
		curl_easy_setopt(cUrl, CURLOPT_POSTFIELDS, "name=Hello&extra=, World");
		/* Set up to store response */

		curl_easy_setopt(cUrl, CURLOPT_WRITEFUNCTION, append_to_string); // set the write callback function
		curl_easy_setopt(cUrl, CURLOPT_WRITEDATA, ptr_string); // to which this pointer is to be passed as the last argument 
		/* perform */
		res = curl_easy_perform(cUrl);
		if (res != CURLE_OK)
			printf("Whoops! Failed to perform! %s\n", curl_easy_strerror(res));
		curl_easy_cleanup(cUrl);
	}
	curl_global_cleanup();
	printf("\nDone!\nOutput: %s", recd_string);
	getch();
    return 0;
}

and it outputs
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Done!
Output: hsù
JLBorges (13770)
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// printf("\nDone!\nOutput: %s", recd_string);
std::cout << "\nDone! received  " << recd_string.size() << "bytes.\n"
          << "output:\n" <<  recd_string << '\n' ;


or: printf("\nDone!\nOutput: %s", recd_string.c_str() );


Tip: enforce conformance to C++ to the extent possible and enable warnings;
the compiler would alert you of many possible errors if you do.

Microsoft (warning): 
source_file.cpp(10): warning C4477: 'printf' : format string '%s' requires an argument of type 'char *', but variadic argument 1 has type 'std::string'

http://rextester.com/UQYP1701

LLVM (error):
main.cpp:10:41: error: cannot pass non-trivial object of type 'std::string' (aka 'basic_string<char, char_traits<char>, allocator<char> >') to variadic function; expected type from format string was 'char *' [-Wnon-pod-varargs]
    std::printf( "\nDone!\nOutput: %s", recd_string ) ;
                                   ~~   ^~~~~~~~~~~
main.cpp:10:41: note: did you mean to call the c_str() method?
    std::printf( "\nDone!\nOutput: %s", recd_string ) ;
                                        ^
                                                   .c_str()
1 error generated.

http://coliru.stacked-crooked.com/a/e5c1bf46dc953db3

GNU (warning):
main.cpp: In function 'int main()':
main.cpp:10:53: warning: format '%s' expects argument of type 'char*', but argument 2 has type 'std::__cxx11::string* {aka std::__cxx11::basic_string<char>*}' [-Wformat=]
     std::printf( "\nDone!\nOutput: %s", recd_string ) ;
                                                     ^

http://coliru.stacked-crooked.com/a/e5c1bf46dc953db3
ExSanity (82)
Thank you :)
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