I have successufully compiled my spellcheck program and libspellcheck library. Now my problem is allowing other developers to use my libspellcheck. I created a simple test program:
#include <spellcheck.h>
#include <iostream>
using namespace std;
int main(void)
{
bool spell_result = check_spelling("english.dict", "abed");
if(spell_result == true)
{
cout << "your dictionary / libspellcheck works!" << endl;
}
else
{
cout << "problem with your dictionary / libspellcheck" << endl;
}
return 0;
}
If everything is functioning fine, the program will output:
your dictionary / libspellcheck works
However, this program won't even compile. I used:
g++ -lspellcheck -o test test.cpp
And it did not work. I believe this is a problem with the header file, as the compiler gives me this:
test.cpp: In function ‘int main()’:
test.cpp:9:59: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]
test.cpp:9:59: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]
/tmp/ccIz3ivT.o: In function `main':
test.cpp:(.text+0x19): undefined reference to `check_spelling(char*, char*)'
collect2: ld returned 1 exit status
The only problem is, spellcheck.h is located in /usr/include, which is where I believe it should be. My question is, how do I fix this error, and was a it a problem with my header file or was it a problem with my libspellcheck. If you need to look at additional code, I will gladly provide it, as spellcheck and libspellcheck are licensed under the GPL.
Assuming your check_spelling declaration in header is correct, try this:
g++ -o test test.cpp -lspellcheck
(-l should be after the objects depending on the libraries in the command line). As of the header, it is indeed found and used, or you would get an error from the compiler, not the linker.
Related
I'm trying to build a write of software with the Tensor module provided as unsupported from eigen3. I've written a simple piece of code that will build with a simple application of VectorXd (just printing it to stdout), and will also build with an analogous application of Tensor in place of the VectorXd, but WILL NOT build when I do not throw an optimization flag (-On). Note that my build is from within a conda enviromnent that is using conda-forge compilers, so the g++ in what follows is the g++ obtained from conda forge for ubuntu. It says its name in the error messages following, if that is perceived to be the issue.
I have a feeling this is not about the program I'm trying to write, but just in case I've included an mwe.cpp that seems to produce the error. The code follows:
#include <eigen3/Eigen/Dense>
#include <eigen3/unsupported/Eigen/CXX11/Tensor>
#include <iostream>
using namespace Eigen;
using namespace std;
int main(int argc, char const *argv[])
{
VectorXd v(6);
v << 1, 2, 3, 4, 5, 6;
cout << v.cwiseSqrt() << "\n";
Tensor<double, 1> t(6);
for (auto i=0; i<v.size(); i++){
t(i) = v(i);
}
cout << "\n";
for (auto i=0; i<t.size(); i++){
cout << t(i) << " ";
}
cout << "\n";
return 0;
}
If the above code is compiled without any optimizations, like:
g++ -I ~/miniconda3/envs/myenv/include/ mwe.cpp -o mwe
I get the following compiler error:
/home/myname/miniconda3/envs/myenv/bin/../lib/gcc/x86_64-conda_cos6-linux-gnu/7.3.0/../../../../x86_64-conda_cos6-linux-gnu/bin/ld: /tmp/cc2q8gj4.o: in function `Eigen::internal::(anonymous namespace)::get_random_seed()':
mwe.cpp:(.text+0x15): undefined reference to `clock_gettime'
collect2: error: ld returned 1 exit status
If instead I ask for 'n' optimization level, like the following:
g++ -I ~/miniconda3/envs/loos/include/ -On mwe.cpp -o mwe
The program builds without complaint and I get expected output:
$ ./mwe
1
1.41421
1.73205
2
2.23607
2.44949
1 2 3 4 5 6
I have no clue why this little program, or the real program I'm trying to write, would be trying to get a random seed for anything. Any advice would be appreciated. The reason why I would like to build without optimization is so that debugging is easier. I actually thought all this was being caused by debug flags, but I realized that my build tool's debug setting didn't ask for optimization and narrowed that down to the apparent cause. If I throw -g -O1 I do not see the error.
Obviously, if one were to comment out all the code that has to do with the Tensor module, that is everthing in main above 'return' and below the cwiseSqrt() line, and also the include statement, the code builds and produces expected output.
Technically, this is a linker error (g++ calls the compiler as well as the linker, depending on the command line arguments). And you get linker-errors if an externally defined function is called from somewhere, even if the code is never reached.
When compiling with optimizations enabled, g++ will optimize away uncalled functions (outside the global namespace), thus you get no linker errors. You may want to try -Og instead of -O1 for better debugging experience.
The following code should produce similar behavior:
int foo(); // externally defined
namespace { // anonymous namespace
// defined inside this module, but never called
int bar() {
return foo();
}
}
int main() {
// if you un-comment this line, the
// optimized version will fail as well:
// ::bar();
}
According to man clock_gettime you need to link with -lrt if your glibc version is older than 2.17 -- maybe that is the case for your setup:
g++ -I ~/miniconda3/envs/myenv/include/ mwe.cpp -o mwe -lrt
I'm writing software to control a bladeRF radio card but I'm running into a strange compiler/linker error that I haven't been able to figure out. My code uses several functions and data structures defined in the library, libbladeRF, but for some reason I can't reference to one specific function.
However, if I modify the call with an improper argument type, g++ will throw an error to let me know that it doesn't conform to the definition, which seems to tell me that the linker is actually able to locate the reference.
What am I missing?
Initial error:
$ g++ bladeRF_test.cpp -o bladeRF_test -lbladeRF
/tmp/ccTWZzdJ.o: In function `enable_xb300()':
bladeRF_test.cpp:(.text+0x36a): undefined reference to `bladerf_xb300_set_amplifier_enable'
Code excerpt:
#include <iostream>
#include <string>
#include <libbladeRF.h>
using namespace std;
...
int set_xb300_pa(bool enable) {
bladerf_xb300_amplifier amp = BLADERF_XB300_AMP_PA;
if ( bladerf_xb300_set_amplifier_enable(dev, amp, enable) ) {
// Print error message
return -1;
} else {
// Print success message
return 0;
}
}
...
Function arguments changed from (dev, amp, enable) to (&dev, amp, enable):
$ g++ blade_hello.cpp -o blade_hello -lbladeRF
blade_hello.cpp: In function ‘int set_xb300_pa()’:
blade_hello.cpp:62:59: error: cannot convert ‘bladerf**’ to ‘bladerf*’ for argument ‘1’ to ‘int bladerf_xb300_set_amplifier_enable(bladerf*, bladerf_xb300_amplifier, bool)
^
In file included from blade_hello.cpp:4:0:
/usr/local/include/libbladeRF.h:2226:15: note: declared here
int CALL_CONV bladerf_xb300_set_amplifier_enable(struct bladerf *dev,
^
I'm taking an intro class into C++ and we are using jgrasp. I'm doing a simple exercise right now which looks like this:
#include <iostream>
using namespace std;
int main()
{
cout << "Testing 1, 2, 3\n";
return 0;
}
though when I compile it and link it I get this error:
----jGRASP exec: g++ -c -fsyntax-only H:\COP2334\Excerises\Display 1.10
g++.exe: warning: H:\COP2334\Excerises\Display 1.10: linker input file unused because linking not done
----jGRASP: operation complete.
The option -c means "Compile or assemble the source files, but do not link."
So, of course, linking isn't performed.
I've got some code that I'm running on Mac OS X that can't be compiled on the Virtual Machine running Linux Mint. This is a simple example. When I run it in Mac, all is fine, but I'm getting issues when I run the same code on Linux, so I'm assuming the library I'm including is not there, but should I be getting an include error then?
Here's the example code that runs on Mac.
#include <iostream>
#include <stdlib.h>
#include <string>
#include <cstdlib>
using namespace std;
int main(){
for (int i = 0; i < 10; i++){
string test = to_string(i);
cout << test << endl;
}
cout << "done" << endl;
return 0;
}
I get no issues here but running on Linux Mint, I get this when I try to compile:
for.cpp: In function 'int main()':
for.cpp:7:28 error: 'to_string' was not declared in this scope
string test = to_string(i);
^
make: *** [for] Error 1
Am I missing something? Any help would be much appreciated!
edit
I realize I forgot to include <string> on here and I fixed it, but what I changed (<string> included) still doesn't compile on Linux. I've used to_string before. I know that much in C++. I also tried adding <cstdlib>. Once again, this DOES compile on Mac and DOES NOT compile on Linux.
Here is my OSX output:
0
1
2
3
4
5
6
7
8
9
done
Here is my output on Linux Mint (Once again, Virtual Box, g++ make):
test.cpp: In function ‘int main()’:
test.cpp:9:28: error: ‘to_string’ was not declared in this scope
string test = to_string(i);
^
make: *** [test] Error 1
You could reproduce the problem yourself if you don't believe me. It's the same code, you can see for yourself if you want.
Compile your for.cpp file like this:
g++ -std=c++11 for.cpp
and run it with:
./a.out
The support for the to_string function in the <string> header was added in the C++11 version of the language, so you need to tell GCC to use that version. You can use the c++0x flag too, for example:
g++ -std=c++0x for.cpp
And you don't have to worry about <cstdlib>, that has nothing to do with it...
to_string() is defined in <string> if you are compiling with C++11 (but is not defined, or unreliably defined as an extension feature, if you are compiling with an earlier version of C++).
Reference: http://en.cppreference.com/w/cpp/string/basic_string/to_string
SOLUTION:
I found a better solution. For some reason, I've read stdlib.h will not work on some linux systems. I used a different function to convert int to string.
on linux:
#include <stdio.h>
and then
for (int i = 0; i < 10; i++){
char buffer[10];
sprintf(buffer,"%d",i);
string stringInt = buffer;
cout << stringInt << endl;
// do whatever you want with the string
}
edit
To the person that down voted my solution to this, here's a post from six years ago basically saying the same thing.
I've been learning C++ and using the Terminal for the last couple of months. My code was compiling and running fine using g++ and C++11, but in the last couple of days it started giving errors and I have had problems compiling since. The only programs I can compile and run depend on older C++ standards.
The errors I first got related to #include < array > in the header file. Not sure why this happened, but I got around it by using boost/array instead. Another error I can't solve is with std::stoi. Both array and stoi should be in the C++11 standard library. I made the following simple code to demonstrate what's going on:
//
// stoi_test.cpp
//
// Created by ecg
//
#include <iostream>
#include <string> // stoi should be in here
int main() {
std::string test = "12345";
int myint = std::stoi(test); // using stoi, specifying in standard library
std::cout << myint << '\n'; // printing the integer
return(0);
}
Try to compile using ecg$ g++ -o stoi_trial stoi_trial.cpp -std=c++11
array.cpp:13:22: error: no member named 'stoi' in namespace 'std'; did you mean
'atoi'?
int myint = std::stoi(test);
~~~~~^~~~
atoi
/usr/include/stdlib.h:149:6: note: 'atoi' declared here
int atoi(const char *);
^
array.cpp:13:27: error: no viable conversion from 'std::string' (aka
'basic_string') to 'const char *'
int myint = std::stoi(test);
^~~~
/usr/include/stdlib.h:149:23: note: passing argument to parameter here
int atoi(const char *);
^
2 errors generated.
I also get these errors at compilation when using gcc or clang++ and with -std=gnu++11 (I guess they all depend on the same file structure). I also get the same error whether I specify std:: in the code, or if I specify using namespace std;
I worry that these issues arose because of the September Command Line Tools update via Xcode or because I installed boost and this somehow messed up my C++11 libraries. Hopefully there is a simple solution.
My system:
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-> dir=/usr/include/c++/4.2.1
Apple LLVM version 5.0 (clang-500.2.76) (based on LLVM 3.3svn)
Target: x86_64-apple-darwin12.5.0
Thread model: posix
Thanks for any insight you can offer.
clang has a weird stdlib, you need to add the following flag when you compile
-stdlib=libc++
your snippet works on my mac with
g++ -std=gnu++11 -stdlib=libc++ test.cpp -o test
This answer describes the problem