When I compile my secrypt.cpp program, my compiler shows the error "undefined reference to WinMain#16".
my code is as follows
secrypt.h :
#ifndef SECRYPT_H
#define SECRYPT_H
void jRegister();
#endif
secrypt.cpp :
#include<iostream>
#include<string>
#include<fstream>
#include<cstdlib>
#include "secrypt.h"
using namespace std;
void jRegister()
{
ofstream outRegister( "useraccount.dat", ios::out );
if ( !outRegister ) {
cerr << "File could not be opened" << endl;
exit( 1 );}
string a,b,c,d;
cout<<"enter your username :";
cin>>a;
cout<<"enter your password :";
cin>>b;
outRegister<<a<<' '<<b<<endl;
cout<<"your account has been created";
}
trial.cpp
#include<iostream>
#include "secrypt.h"
using namespace std;
int main()
{
void jRegister();
return 0;
}
Here is the image of my error:
errorimage
When I compile my trial.cpp program, it compiles and opens the console, but didn't calls the function. Here is the image of the console screen of trial.cpp program .
o/p screen
Can anyone help me solving this?
When there's no project, Code::Blocks only compiles and links the current file. That file, from your picture, is secrypt.cpp, which does not have a main function. In order to compile and link both source files, you'll need to do it manually or add them to the same project.
Contrary to what others are saying, using a Windows subsystem with main will still work, but there will be no console window.
Your other attempt, compiling and linking just trial.cpp, never links secrypt.cpp. This would normally result in an undefined reference to jRegister(), but you've declared the function inside main instead of calling it. Change main to:
int main()
{
jRegister();
return 0;
}
Well I know this answer is not an experienced programmer's approach and of an Old It consultant , but it worked for me .
the answer is "TRY TURNING IT ON AND OFF" .
restart codeblocks and it works well
reminds me of the 2006 comedy show It Crowd .
I was interested in setting up graphics for Code Blocks when I ran into a this error: (took me 2 hrs to solve it)
I guess you need to have a bit of luck with this. In my case i just changed the order of contents in Settings menu->Compiler and Debugger->Global compiler settings->Linker settings->Other Linker Options:
The working sequence is:
-lmingw32
-lSDL
-lSDLmain
You should create a new project in Code::Blocks, and make sure it's 'Console Application'.
Add your .cpp files into the project so they are all compiled and linked together.
You need to open the project file of your program and it should appear on Management panel.
Right click on the project file, then select add file. You should add the 3 source code (secrypt.h, secrypt.cpp, and the trial.cpp)
Compile and enjoy. Hope, I could help you.
Open the project you want to add it.
Right click on the name.
Then select, add in the active project.
Then the cpp file will get its link to cbp.
Hey I had a similar problem, all the files were in same project but still it did not compile them together. Here is what I did
On the left panel, in the Workspace area you can see your project name and files in it.
Right click on the project name and hit rebuild.
This alone helped me, rebuild builds your project again from scratch.
undefined reference to WinMain#16" Visual Studio
if you are using Visual Studio Code then
1)Stetting
2)Search for save
3)scroll down and search for code runner
4)check the checkbox 'Save File Before Run
5)Now run
Saving resolved the issue in my case.
If you're using VS code, then toggle on save before running the code option in the settings. It worked for me.
I had the same error problem using Code Blocks rev 13.12.
I may be wrong here since I am less than a beginner :)
My problem was that I accidentally capitalized "M" in Main() instead of ALL lowercase = main() - once corrected, it worked!!!
I noticed that you have "int main()" instead of "main()". Is this the problem, or is it supposed to be that way?
Hope I could help...
Related
I have found two similar questions this and this .
But they both use opencv, and opencv indeed provide the corresponding lib. I don't use opencv, and my project is very simple, just hello world.I have changed project default configuration like this
except for these configurations, others all take defaults
I just want to test my project configuration，that works find for win32 debug and release. But not work for x64 debug and release, they all tell me LINK : fatal error LNK1104: cannot open file 'opencv_world341d.lib'
I indeed know my project does not use any opencv lib, but why they tell me I need to use opencv_world341d.lib
my code
#include<iostream>
using namespace std;
int main()
{
cout << "hello world" << endl;
}
Thanks for everyone who comments on the question. I have solved the problem, although this problem not relevant to OpenCV to much, but I think the solution to the problem may be helpful to others. When I build project, visual studio 2019 tell me cannot link opencv_world341d.lib, so I go to Project->Properties->Linker->Input->Additional Dependencies , and I found opencv_world341d.lib. So I need to remove it, but it's readonly. From this we know visual studio using settings file (Microsoft.cpp..users.props) to control global settings including Global search path. These files are located at $(USERPROFILE)\appdata\local\microsoft\msbuild\v4.0 directory. Then I reedit Microsoft.cpp.<Platform>.users.props, delete opencv_world341d.lib, reboot visual studio, problem solved.
So finally I’m not able to help myself out by researching anymore. Hopefully you can help me.
I recently decided to learn C++ in the context of my bachelor-thesis: My first aim is to read the pixel-values of a tiff-image with the libtiff-library. Yet, every call of a function of the library seems to break parts of my program.
Here’s the simple “HelloWorld”-Program, it works as it should:
#include "tiffio.h"
#include <iostream>
using namespace std;
int main() {
cout << "Hello" << endl;
// TIFF* tif = TIFFOpen("path to .tif", "r");
return 0;
}
When I uncomment the second line in main(), the code still does compile without errors (except the warning that ‘tif’ isn’t used) and I can start the program as usual. Yet nothing gets printed into the console anymore. Not “Hello” nor any errors.
Any suggestions where the error could be? The code should be alright, I guess I messed something up during the setup of the library or so. Here’s what I did:
I managed to set up eclipse (Mars, 32bit) for C++ and MinGW (32bit) on my 64bit Win7, then downloaded libtiff 4.0.4 and built it following this instruction.
I created a new C++-project with the mentioned code and did the following adjustments in the project-properties:
Project->Properties->C/C++ General->Paths and Symbols->Library
Paths-> Added “D:/… /tiff-4.0.4/libtiff/.libs”
Project->Properties->C/C++ Build->MinGW C++
Linker->Miscellaneous->Set Linkerflags to “-static-libgcc
-static-libstdc++”
Project->Properties->C/C++ Build->MinGW C++ Linker->Libraries-> Set
(-L) to “D:/… /tiff-4.0.4/libtiff/.libs” and (-l) to “libtiff”
I know the .tif is a valid file as I implemented parts of my program in C#, using the LibTiff.NET library by BitMiracle.
Thank you in advance!
Edit 1: The same error occures, even if TIFF* tif = TIFFOpen("path to .tif", "r"); is never called but written down in a dead part of the code. Debugging does not work either, the program seems to be terminated (exit value 0) before a single line is executed, without any error-reports.
I had the same issue and managed to get rid of it.
I set up eclipse (Mars) for C++ and MinGW on my 64bit Win7, then downloaded libtiff 4.0.4 and built it following this instruction.
After the build, I got two directories containing files:
include
tiff.h
tiffconf.h
tiffio.h
tiffio.hxx
tiffvers.h
lib
libtiff.a
libtiff.dll.a
libtiff.la
libtiffxx.a
libtiffxx.dll.a
libtiffxx.la
I also linked all include files and only the libtiff.a to my project and that solved it, ie, the other lines are now executed.
I hope, I helped with this post.
main.cpp
#include <iostream>
#include <string>
using namespace std;
void echo(string);
int main()
{
echo("hello");
cout << "Hello world!" << endl;
return 0;
}
print.cpp
#include <iostream>
#include <string>
void echo(string code){
cout << code;
}
After compiling the code in code blocks 12.11, it gives me that error:
undefined reference to `echo(std::string)
I use windows 7 x64.
I have added the directory; Project>build options > search directories and added the current working directory.
All the files are in one console project in code blocks
I believe you should read up a bit more on namespaces usage. You are missing std in print.cpp.
Generally, while starting to learn cpp or getting a grip of the language you should always try writing full names of the classes along with the namespaces. Eventually with practice and some oversights (like now) you will learn why you really need them. In a nutshell namespaces are great:
When you are writing code over multiple files
Compartmentalize your code into separate blocks.
Also, using namespace std; should be used within cpp files mostly (otherwise headers get mangled up.
Anyways, try changing your code to this:
#include <iostream>
#include <string>
void echo(std::string code){
std::cout << code;
}
Then your results will look like this:
> g++ main.cpp print.cpp -o a.out
> ./a.out
helloHello world!
You should get more than that linker error, since you use string without any namespace in your print.cpp file. And if that source file doesn't compile it can't be linked with, and you will get the linker error you have.
Change to e.g.
void echo(std::string code) { ... }
And you do try to link with the object file created from print.cpp ?
I know this is old, but for anyone looking to solve this issue, the following may be a solution for you. If you have g++ follow c++ 11 under project->build options (check your options anyway) then you must check that box for all files you make in the project for the error to be cleared up. I had that annoying undefined reference thing too but now it is gone!
Try "Project/Properties/Build Targets tab". There you should find "Build target files" field. In that filed find "print.cpp" and click the checkbox (now the compiler will build print.cpp).
Some usefull information on Project management in CB
http://www.codeblocks.org/docs/main_codeblocks_en.html
When dealing with strings in C++ its best to sue std::string and your code seems to be wrong with a changes like using std::cout instead of plain cout another thing you need to be careful is linking your files especially files in different directories you need to tell code blocks were to find this print.cpp by going to build option and go for the search tab directory and point to where print.cpp is other wise the other approach is to just build a project which will have the main.cpp and and then add print.cpp class to current project I hope this will be of some help
I keep getting this error with these lines of code:
include <iostream>
int main()
{
cout << "Hello World" >>;
system("pause");
return 0;
}
"The system cannot find the file specified"
The system cannot find the file specified usually means the build failed (which it will for your code as you're missing a # infront of include, you have a stray >> at the end of your cout line and you need std:: infront of cout) but you have the 'run anyway' option checked which means it runs an executable that doesn't exist. Hit F7 to just do a build and make sure it says '0 errors' before you try running it.
Code which builds and runs:
#include <iostream>
int main()
{
std::cout << "Hello World";
system("pause");
return 0;
}
The code should be :
#include <iostream>
using namespace std;
int main() {
cout << "Hello World";
return 0;
}
Or maybe :
#include <iostream>
int main() {
std::cout << "Hello World";
return 0;
}
Just a quick note: I have deleted the system command, because I heard it's not a good practice to use it. (but of course, you can add it for this kind of program)
I had a same problem and this fixed it:
You should add:
C:\Program Files (x86)\Microsoft SDKs\Windows\v7.1A\Lib\x64 for 64 bit system
C:\Program Files (x86)\Microsoft SDKs\Windows\v7.1A\Lib for 32 bit system
in Property Manager>Linker>General>Additional Library Directories
Another take on this that hasn't been mentioned here is that, when in debug, the project may build, but it won't run, giving the error message displayed in the question.
If this is the case, another option to look at is the output file versus the target file. These should match.
A quick way to check the output file is to go to the project's property pages, then go to Configuration Properties -> Linker -> General (In VS 2013 - exact path may vary depending on IDE version).
There is an "Output File" setting. If it is not $(OutDir)$(TargetName)$(TargetExt), then you may run into issues.
This is also discussed in more detail here.
This is because you have not compiled it. Click 'Project > compile'. Then, either click 'start debugging', or 'start without debugging'.
I resolved this issue after deleting folder where I was trying to add the file in Visual Studio. Deleted folder from window explorer also. After doing all this, successfully able to add folder and file.
I was getting the error because of two things.
I opened an empty project
I didn't add #include "stdafx.h"
It ran successfully on the win 32 console.
I'm trying a very basic C++ program using Code::Blocks. I'm on Ubuntu 12.04 and installed pqxx from the software manager. Here's the code.
#include <pqxx/pqxx>
#include <iostream>
using namespace std;
int main()
{
pqxx::connection MyConn ("dbname=dbESM user=postgres");
cout << "Hello world!" << endl;
return 0;
}
But I get the following error on hitting F9 to compile and run:
/usr/include/pqxx/connection.hxx|87|undefined reference to
`pqxx::connectionpolicy::connectionpolicy(std::basic_string, std::allocator > const&)'
The above message is from the file connection.hxx and the line highlighted is this:
explicit connect_direct(const PGSTD::string &opts) : connectionpolicy(opts) {}
The connection.hxx file is not mine - I think it's part of pqxx.
I'm pretty new to this platform so I'm avoiding the terminal to compile code. Any help would be greatly appreciated.
You need to add the reference to the libpqxx library to the project.
Inside Code::blocks, when the project is open, locate Project in the menus, then follow Build options, then open the tab called Linker settings, then hit Add, then enter pqxx.
If you were using the libpq C library instead, the procedure would be identical except the name would be pq.
You need to link against the according library, just #including the header files isn't enough. If available, you could use pkg-config to determine the according libraries. Further, what IDE are you using? Without that, the "on hitting F9" reference is useless. Also, compiling this on the commandline might even be easier, since it is clearer what exactly is happening.