Header files in dev-C++

问题

I'm trying to add an header file to dev-C++ but when I compile it it doesn't work. Here are my exact steps (for my example, I'm trying to get mysql.h to work):

copy "mysql.h" into c:\dev-c++\includes
check that in dev-C++ tools > compiler options > directories > c includes and c++ includes have the path to "c:\dev-c++\includes"
include #include at the top of my file
compiled

This is what the dev-C++ compiler told me:

13 C:\Documents and Settings\Steve\Desktop\server code\setup1\main.c `mysql' undeclared (first use in this function)

As well as other errors due to not locating the header file

Are the steps I've outlined correct? Or is there something else I need to do to get the header files to compile.

P.S. I tried doing the same with VS2008 (put mysql.h in the vs2008 include folder, etc) but still have the same error. I would like to stick with Dev-c++ if possible.

回答1:

Dev-C++ is a port of GCC, so try this page: http://gcc.gnu.org/onlinedocs/cpp/Search-Path.html.

Note that you probably have to tinkle with the Makefile.

回答2:

You didn't say how you included it at the top of your file. This should work if you did

#include "mysql.h"

rather than

#include <mysql>

which is a mistake that people sometimes make.

EDIT: Perhaps try using relative paths rather than an absolute path (as you seem to be doing) when specifying additional include directories? I don't know if that would make a difference (and I don't have the time to check) but I've always used relative paths and it's always worked for me (it's also good practice anyway). So, instead of

C:\Projects\ProjectName\Include

something like

\Include or ..\Include depending on your project file structure.

回答3:

I had the same problem....

You need to put the #include after "using namespace std;", in order to use your header file in the standard namespace.

For me it is working.

Best wishes.

回答4:

On the left side, right click the Project and choose "Add to Project", and then select the header file.

回答5:

Its very simple ...

Just make Your header file and save it as .h extension.

Then use #include "file_name.h" instead of using include

Example- This is my header file.

#include<iostream>
     using namespace std;

     namespace Ritesh
         {
             int a;
             int b;
             void sum();
         }
     void Ritesh::sum()
         {
             cout<<a+b;
         }

Then use of it-

#include<iostream>
#include "Ritesh.h"
   using namespace std;
   using namespace Ritesh;
   int main()
       {
           a=4;b=6;
           sum();
       }

Output- Output of program

来源：https://stackoverflow.com/questions/257795/header-files-in-dev-c

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file

header

dev-c++