I am working with the windows.h functions and everything works fine so far.
But when I try to use functions which require me to link external libraries something goes wrong.
In this case I am trying to use CreateFont(). I already know that I must link libwinmm.a and libgdi32.a and I've done that:
See this screenshot
But when I try to build the project i get following error messages:
g++ "-LD:\\Programme\\Eclipse\\lib" -o GameTest.exe "src\\choosemealmain.o" "src\\mealchooser.o" "-lD:\\Programme\\Eclipse\\lib\\libwinmm.a" "-lD:\\Programme\\Eclipse\\lib\\libgdi32.a"
d:/programme/eclipse/bin/../lib/gcc/mingw32/6.3.0/../../../../mingw32/bin/ld.exe: cannot find -lD:\Programme\Eclipse\lib\libwinmm.a
d:/programme/eclipse/bin/../lib/gcc/mingw32/6.3.0/../../../../mingw32/bin/ld.exe: cannot find -lD:\Programme\Eclipse\lib\libgdi32.a
collect2.exe: error: ld returned 1 exit status
I made sure to doublecheck whether the mentioned libraries are actually to be found in the mentioned path and they are.
I would be glad for any kind of help!
You are wrongly using quotes with -l flag. The -l flag also automatically adds the lib prefix and the .a extension. Your command line should be:
g++ -LD:\Programme\Eclipse\lib -o GameTest.exe "src\choosemealmain.o" "src\mealchooser.o" -lwinmm -lgdi32
I am trying to use Microsoft REST SDK to create a server listening to HTTP requests. My current computer is Ubuntu 18.04, the server code is pretty simple.
I have already installed the library by following the instructions on libboost official website and I have checked files in /usr/local/lib/, there are libboost_random.so.1.68.0 so I presume that I have libboost library.
However when I try to compile the code with the following command:
g++ server.cpp -o server -lpthread -lcpprest -lcrypto -lssl -lboost_system
It shows:
/tmp/ccKWADuo.o: In function `boost::system::system_category()':
server.cpp:(.text._ZN5boost6system15system_categoryEv[_ZN5boost6system15system_categoryEv]+0x7): undefined reference to `boost::system::detail::system_category_instance'
/tmp/ccKWADuo.o: In function `boost::system::generic_category()':
server.cpp:(.text._ZN5boost6system16generic_categoryEv[_ZN5boost6system16generic_categoryEv]+0x7): undefined reference to `boost::system::detail::generic_category_instance'
collect2: error: ld returned 1 exit status
Thanks for any advices.
Boost consists of several independent libraries. Your linker error suggests you are missing libboost_system.so. You just mentioned libboost_random.so to be in your /usr/local/lib but is there also the required libboost_system.so?
[Problem solved] Reinstalling library libboost 1.68.0 helps. Error occurs when building from source, fixing those building errors will solve the problem.
I am trying to compile my C++ code in Windows cmd.
I have implemented UnitTest++ in the project. When I run:
g++ main.cpp -IC:\Test\TreeObjModel\include -IC:\Test\unittest-cpp-master\UnitTest++
it gives the following error:
undefined reference to `UnitTest::RunAllTests()' collect2.exe: error:
ld returned 1 exit status
Can anyone help me to resolve this? Is any more info needed?
You probably are missing to compile some other cpp file (UnitTest.cpp?); or maybe you must link to some UnitTest library, where the code for UnitTest::RunAllTests() resides.
The command line option for linking a library with GCC is -l library_name.
I downloaded the libcurl curl-7.34.0-devel-mingw32.zip from http://curl.haxx.se/gknw.net/7.34.0/dist-w32/curl-7.34.0-devel-mingw32.zip.
I use Eclipse Kepler with MinGW as the toolchain (GCC compiler). I created html.cpp and then test the code from the example http://curl.haxx.se/libcurl/c/simple.html:
I included the headers:
#include<iostream>
#include<curl/curl.h>
using namespace std;
There are 5 cURL functions. Only 2 of them (curl_easy_init,curl_easy_setopt)are said to be 'undefined reference'.
The compiler message:
Info: Internal Builder is used for build
g++ -O3 -Wall -c -fmessage-length=0 -o html.o "..\\html.cpp"
g++ -static-libgcc -static-libstdc++ -o HTML.exe html.o
html.o:html.cpp:(.text.startup+0x12): undefined reference to `_imp__curl_easy_init'
html.o:html.cpp:(.text.startup+0x1e): undefined reference to `_imp__curl_easy_setopt'
c:/mingw/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: html.o: bad reloc address 0x1e in section `.text.startup'
c:/mingw/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: final link failed: Invalid operation
collect2.exe: error: ld returned 1 exit status
The other 3 functions said to be fine:
curl_easy_perform
curl_easy_strerror
curl_easy_cleanup
I have tried to set to properties to tell the MinGW linker to include the headers and library files. The same situation as the above or the compiler simply says the .a files not found. Adding -lcurl or -DCURL_STATICLIB to the linker's flag is useless as well.
I have also tried to copy the libraries(.a files) and the headers(.h files) of libcurl to the folders bin, include and lib inside C:\MinGW and C:\gcc-4.8.1. It turns out to be no change.
Sadly, the first challenge of using cURL is not coding but the compilation. How can I solve this problem?
Thanks you guys!
I need to use libcurl in a piece of software I am writing on my ubuntu machine. I am using Eclipse to write and compile all of the software. When I put the libcurl files in the same folder as the .cpp file, and include the curl.h file in the header, When I attempt to compile the program, It comes up with these errors:
Building target: sms
Invoking: GCC C++ Linker
g++ -o"sms" ./src/sms.o
./src/sms.o: In function `main':
/home/geekman/workspace/sms/Debug/../src/sms.cpp:38: undefined reference to `curl_easy_init'
/home/geekman/workspace/sms/Debug/../src/sms.cpp:42: undefined reference to `curl_easy_setopt'
/home/geekman/workspace/sms/Debug/../src/sms.cpp:44: undefined reference to `curl_easy_setopt'
/home/geekman/workspace/sms/Debug/../src/sms.cpp:46: undefined reference to `curl_easy_perform'
/home/geekman/workspace/sms/Debug/../src/sms.cpp:47: undefined reference to `curl_easy_cleanup'
collect2: ld returned 1 exit status
make: *** [sms] Error 1
I took the contents of the include folder from libcurl, and placed them in the same folder as the .cpp file. then in the header of the .cpp file, I typed:
#include <curl/curl.h>
I also tried:
#include "curl/curl.h"
Any ideas on the problem? Thanks.
Your header file inclusions are just fine; your problem is occurring at the linking step. In order to link against libcurl, you need to add the -lcurl command line option, assuming it's installed in a standard directory:
g++ -o sms ./src/sms.o -lcurl
If it's not installed in a standard directory, you also need to add the -L/path/to/libcurl, e.g. something like:
# Assuming that /home/geekman/workspace/libcurl is where libcurl.a is located
g++ -o sms ./src/sms.o -L/home/geekman/workspace/libcurl -lcurl
Also note that the -lcurl option has to appear after the list of object files you're linking, otherwise it won't link properly.
You can try to use curl-config --libs.
An alternate answer (the first one is excellent). Consider using the output returned by "pkg-config --libs libcurl" as an argument to your compiler.
For example,
CPPFLAGS=`pkg-config --libs libcurl`
g++ $CPPFLAGS myfile.o
Pkg-config is a standard way for open source libraries to communicate to you how to link against them / #include their files.
Anyone who is using ecplise CDT then you need to do following. First on terminal enter
curl-config --libs
On my machine, the result is
-L/usr/lib/i386-linux-gnu -lcurl
then do according to this screenshot and you will be able to compile. btw don't forget to add header files in your code
So you enter library folder path without -L and library name without -l because they will be automatically added by linker.
You have to link the library to your program. With gcc (and most other compilers) you can specify the libraries to link with -lname_wo_lib, e.g. -lcurl
Also see GNU GCC Manual - Options for Linking for a detailed explanation of the options Adam Rosenfield said. For standard search directories, see An Introduction to GCC - for the GNU Compilers gcc and g++ - Setting Search Paths.
In addition to the first answer, I had to link the curlpp library too. So to compile the main.cpp file which included the curlpp I had to do:
g++ main.cpp -lcurl -lcurlpp
Using only one of the two links would return different errors regarding different links. It is important to remind that this only worked because I had installed all the necessary libraries in the standard include folders