Creating classes in other files

[eric johnson]

Hello, I am totally new to c++ and programming in general, and am running into issues when trying to create classes in other files. All I want my code to do is print a message, "Howdy", when an object is made. I am using the following codes with CodeBlocks on Mac OS X 10.10.3:

main.cpp

#include <iostream>
#include "Milo.h"

using namespace std;

int main()
{
    Milo ob;
    return 0;
}

Milo.h

#ifndef MILO_H
#define MILO_H


class Milo
{
    public:
        Milo();

};

#endif // MILO_H 

Milo.cpp

#include "Milo.h"
#include <iostream>

using namespace std;

Milo::Milo()
{
    cout << "Howdy" << endl;
}

However, whenever I build/run main.cpp, instead of printing "Howdy", CodeBlocks runs whatever main.cpp contained the last time it was built/ran. For example, in this case it printed "Hello World!" instead of "Howdy" since I initially built/ran main.cpp when it contained the generic "Hello world" code.

The build log shows:

-------------- Build: Debug in newClass (compiler: GNU GCC Compiler)---------------

g++ -Wall -fexceptions -g -I -c /Users/Ek/Desktop/newClass/main.cpp -o obj/Debug/main.o
Undefined symbols for architecture x86_64:
"Milo::Milo()", referenced from:
_main in main-7c0b9c.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Process terminated with status 1 (0 minute(s), 0 second(s))
0 error(s), 0 warning(s) (0 minute(s), 0 second(s))


-------------- Run: Debug in newClass (compiler: GNU GCC Compiler)---------------

Checking for existence: /Users/Ek/Desktop/newClass/bin/Debug/newClass
Executing: osascript -e 'tell app "Terminal"' -e 'activate' -e 'do script "/Users/Ek/Downloads/CodeBlocks.app/Contents/MacOS/cb_console_runner DYLD_LIBRARY_PATH=$DYLD_LIBRARY_PATH:. /Users/Ek/Desktop/newClass/bin/Debug/newClass "' -e 'end tell' (in /Users/Ek/Desktop/newClass/.)
Process terminated with status 0 (0 minute(s), 0 second(s))


If instead I do not initially run the "Hello world" code, I get a pop up box when I run/build main.cpp with the following message:

"It seems this project has not been built yet. Do you want to build it now?"

If I say yes, nothing happens, and I receive the following message in the build log:


-------------- Build: Debug in testd (compiler: GNU GCC Compiler)---------------

g++ -Wall -fexceptions -g -I -c /Users/Ek/Desktop/testd/main.cpp -o obj/Debug/main.o
Undefined symbols for architecture x86_64:
"Milo::Milo()", referenced from:
_main in main-4e0535.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)


I do not encounter this issue if I create the class within main.cpp. Any help would be greatly appreciated. Please let me know if I should provide any additional information.

[Drakonaut]

Hmmm...it prints fine on my Codeblocks (13.12 | 4.7.1) though.

Do you want to check if there are any boxes un-checked for your .cpp files? I think it is your compiler settings.

[eric johnson]

Thanks, would these boxes be under settings < compiler? I reset the compiler settings, but the same problem persists.

Also, I'm running Codeblocks 13.12 as well.

[Drakonaut]

Right click your .cpp files (the list on the left) and click properties.

[eric johnson]

Both the "Compile file" and "Link file" boxes are checked, as well as the "Debug" and "Release" boxes under the "Belongs in targets:" heading. The "File is read-only " box is unchecked.