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This was the most appropriate place that I saw to post a C build system question that I saw so, sorry if there is a better place that I missed. Anyhow, I have run into an issue running configure where the linker is not finding the library that I'm specifying. I'm down to guesses so, any direction would be helpful. The configure command that I've constructed is below but, basically, I'm using LDFLAGS to point to the .so file that resides in a non-standard location. I'm using CFLAGS to point to the includes directory where the header files reside and LIBS to indicate the library that I'm using. There is another directory /usr/local/bin that contains three binaries that I don't know how to specify with the configure command. I'm trying to build GNU TLS from source after installing Nettle from the source files as well. Thank you in advance!
./configure CFLAGS="-I/usr/local/include/nettle/" LDFLAGS="-L/usr/local/lib64" LIBS="-lnettle"
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Hi,
I think on Linux the LD_LIBRARY_PATH environment variable is used to find shared libs. You might be looking for ldconfig and /etc/ld.so.conf if you are on Linux.
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You don't say whether make completes successfully or not. The compiler flags given tell the compiler where to find the pieces to buld the program. If the compile has completed successfully, but when you try to run the program you get a message
"error while loading shared libraries: <libname.so>: cannot open shared object file: No such file or directory then the problem is at runtime, not compile time. As Randor notes, you can tell the link-loader where to find the library with LD_LIBRARY_PATH
k5054@localhost$ LD_LIBRARY_PATH=/usr/local/lib64 myprog arg1 arg2 sets LD_LIBRARY_PATH for the given command. To set for a single session do
k5054@localhost$ export LD_LIBRARY_PATH=/usr/local/lib64
k5054@localhost$ myprog arg1 arg2 You can add that to your shell's .profile file. and it will be set every time you log in. If you want to set this up permanently for all users ont the system, then as root create a file /etc/ld.so.conf.d/local.conf containing the single line
/usr/local/lib64 Now, as root, run ldconfig, and you should be able to run your program from any login, without needing to set LD_LIBRARY_PATH in your .profile or per session/per command.
you can check what libraries are being loaded using the ldd command
<
k5054@localhost$ ldd /bin/bash
linux-vdso.so.1 (0x00007ffebf5f6000)
libtinfo.so.6 => /lib/x86_64-linux-gnu/libtinfo.so.6 (0x00007f7ec6539000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f7ec6533000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f7ec6341000)
/lib64/ld-linux-x86-64.so.2 (0x00007f7ec66b5000)
If the link-loader can't find a library, it will show
libsomelib.so => not found
Keep Calm and Carry On
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Hi,
I am trying to learn factory design pattern in c++, writing a program with separate header files and their class implementations in .cpp files. But i am facing problem. I was trying the ShapeFactory from where we implement Circle and Rectangle.
invalid new-expression of abstract class type 'Circle'
invalid new-expression of abstract class type 'Rectangle'
But i am getting these errors and also few other errors. Can someone please help on this.
Regards
Litu
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"new" ... you can't instantiate an "abstract" class; you need to subclass it first or use an existing derived class.
It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it.
― Confucian Analects: Rules of Confucius about his food
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i wanna ask, what is the best environment for learning C++ for windows application? e.g. Win32 API, Qt, etc...
also, could anyone suggest what's the best e-books for references?
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When (really) learning, they usually start you with Notepad and a command line compiler. The "environment" can suck up most of your time (and disk space).
It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it.
― Confucian Analects: Rules of Confucius about his food
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It depends on what you are trying to learn. If you know C++ then Win32 should be fairly easy. But if you do not know C++ then that is what you need to start with.
Here is a starter for C++: Learn C++[^]
And one for Windows: EFNet #Winprog[^]
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I am compiling some old legacy code with MFC. For this line in cmath.h I get an error:
NODISCARD _Check_return_ inline float round(_In_ float _Xx) noexcept /* strengthened */ {
return _CSTD roundf(_Xx);
}
With first round statement highlighted I get this message:
C2062 type'int' unexpected
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You should inspect the calling code, I believe (the compiler provides full information with the error message).
"In testa che avete, Signor di Ceprano?"
-- Rigoletto
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I don't understand that. It is a compile error in a core library file. I am not allowed to change it. Why would the calling function have anything to say?
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Quote: Why would the calling function have anything to say?
Quote Selected Text
With very high probability the calling code is wrong (possibly making incorrect assumptions on the called function, it passes the wrong type). Maybe a previous implementation of the library had relaxed checks on calling code correctness.
"In testa che avete, Signor di Ceprano?"
-- Rigoletto
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Use your development environment (VS or whatever) to check that there is a #define for each the following:
NODISCARD
_Check_return_
In
_CSTD
And if you're using C instead of C++, noexcept could be the problem. But I can't say, because I only write C++.
EDIT:  type 'int' unexpected suggests that the caller is passing an int, not a float.
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There are plenty of _Check_return_ statements that work.
If there is something wrong with the calling function, I should get a compile error when compiling the cpp file where the function is called? This is an error from inside the include file cmath.h.
Three errors reported, underscore is the highlighted error indication.
Line 210
_NODISCARD _Check_return_ inline float round(_In_ float _Xx) noexcept /* strengthened */ {
return _CSTD roundf(_Xx);
}
Line 446
_NODISCARD _Check_return_ inline long double round(_In_ long double _Xx) noexcept /* strengthened */ {
return _CSTD roundl(_Xx);
}
Line 663
_GENERIC_MATH1(round)
It seems I am not allowed to alter any include file, so I can not experiment with commenting the functions out, etc.
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Check if round is also defined somewhere else, and check that _GENERIC_MATH1 is actually defined. Beyond that, I don't know.
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I would be inclined to look at the preprocessor output to see what all of those non-standard "types" are.
"One man's wage rise is another man's price increase." - Harold Wilson
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles
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Hi,
I am going to point out that you are almost certainly looking at the wrong code location. The C2062 error usually really does mean the 3 letters 'int' were unexpected while parsing the code.
Look around for an int that is declared wrong.
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Is that the full text of the error message? Also what are the few lines either side of that definition?
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Your compiler should have an option to send the output of the preprocessor into a file. Using Visual C/C++, this option is /P, and the output file has an extension of .i .
Run your code through this, and look for cmath.h in the .i file. Then look for the definition of the round() function. You will see what the compiler thinks the round() function is, and your problem should then be obvious. 
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows.
-- 6079 Smith W.
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Hi and thanks for all help.
When I put
#include <cmath>
right under #include stdafx.h it compiled. Don't ask me exactly why. It may be a conflict between math.h and cmath that was solved in this way.
Regards, Haakon S.
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So...
You said that your compiler gave you an error in cmath.h
Haakon S. wrote: For this line in cmath.h I get an error:
Which you solved... "by including cmath.h"
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I honestly don't know what is going on.
Some files had #include <math.h>. Removing this did't help. It reported error in cmath anyway.
When googling "cmath error c2062" I see that others have had the same problem.
Anyway, it seems that I have found the solution.
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Ok C++ is not mt my main language so please bear with me.
For my question I will use this class
class BillingDates
{
public:
BillingDates(std::string InputFile);
void ProcessDates();
rapidjson::Document doc;
std::string InputFile;
std::string YearStartDate;
std::string YearEndDate;
std::string BBFDate;
std::string BillIssueDate;
std::string BillIssueDateLong;
int CurrentFinancialYear = 0;
std::ifstream InputStream;
};
And in my main program I declare a pointer and an object to the class thus
BillingData *bData;
BillingData bData2;
I can then create my pointer so
bData = new BillingDates("path to my file");
how can I create an instance for bData2 ?
I know I can do it like this
BillingData bData2("path to my file");
but that will create a new var and not use my previously declared var.
Hope this makes sense
"I didn't mention the bats - he'd see them soon enough" - Hunter S Thompson - RIP
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If your code looks exactly like posted, compiler will slap you with an error on bData2 line because you don't have a default constructor. You can:
1. Modify the constructor to default to an empty string: BillingDates(std::string InputFile = std::string()) and handle the case when InputFile is the empty string.
2. Create an additional default constructor: BillingDates()
If you need to move data from bData to bData2 you might need a copy constructor: BillingDate (const BillingDate& other).
Mircea
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