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Struggling with including Headers in another header file (C++)


Struggling with including Headers in another header file (C++)

By : user2184105
Date : November 17 2020, 04:01 AM
I hope this helps you . Rename your Neptune Action.h header file to something like Neptune_Action.h and update your header guards after that
code :


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Including headers in header file doesn't make it included in implementation file - or am I just using wrong command to c

Including headers in header file doesn't make it included in implementation file - or am I just using wrong command to c


By : rtriggs
Date : March 29 2020, 07:55 AM
this one helps.
Remove the ... from the function body. Having them is a syntax error.
code :
typedef struct {
    size_t something;
    size_t something_else;
} foo;
  ^^^^
gcc -c my_prog.c -o my_prog.o
How can I stop #including redundant headers when I use header files like these?

How can I stop #including redundant headers when I use header files like these?


By : tan sue heng
Date : March 29 2020, 07:55 AM
fixed the issue. Will look into that further What do you mean by 'include'? The preprocessor statement #include file copies the contents of file and replaces the statement with these contents. This happens no matter
If by 'include' you mean "the statements and symbols in these files will be parsed multiple times causing warnings and errors", then no, the include guards will prevent that.
code :
#ifndef INCLUDE_GUARD
#define INCLUDE_GUARD
// Define to 1 in first block
#define GUARDED 1
#endif

#ifndef INCLUDE_GUARD
#define INCLUDE_GUARD
// Redefine to 2 in second block
#define GUARDED 2
#endif
/* ExampleClient.c */
//#include <stdlib.h>
  #ifndef STDLIB_H
    #define STDLIB_H
    int abs (int number); //etc.
  #endif

//#include <stdio.h>
  #ifndef STDLIB_H
    #define STDLIB_H
    #define NULL 0 //etc.
  #endif

//#include "mpi.h"
  #ifndef MPI_H
    #define MPI_H
    void MPI_Func(void);
  #endif

//#include "foo.h"
  #ifndef FOO_H
    #define FOO_H
    //#include <stdlib.h>
      #ifndef STDLIB_H
        #define STDLIB_H
        int abs (int number); //etc.
      #endif
    //#include "mpi.h"
      #ifndef MPI_H
        #define MPI_H
        void MPI_Func(void);
      #endif
    void foo(void);
  #endif


//#include "bar.h"
  #ifndef BAR_H
    #define BAR_H
    //#include <stdlib.h>
      #ifndef STDLIB_H
        #define STDLIB_H
        int abs (int number); //etc.
      #endif
    //#include "mpi.h"
      #ifndef MPI_H
        #define MPI_H
        void MPI_Func(void);
      #endif
    void bar(void);
#endif

void main(int argc, char *argv[]) {
    foo();
    MPI_Func();
    bar();
    exit(0); // Added missing semicolon
}
#define STDLIB_H
int abs (int number); //etc.
#define STDLIB_H
#define NULL 0 //etc.
#define MPI_H
void MPI_Func(void);
#define FOO_H
void foo(void);
#define BAR_H
void bar(void);
#ifndef FOO_H
#define FOO_H
void foo(void);
#endif
#include <stdlib.h>  // Defines type size_t
#include "mpi.h"     // Declares function MPI_func()

#include "foo.h"     // Include self so type definitions and function declarations
                     // in foo.h are available to all functions in foo.c

void foo(void);
  size_t length;
  char msg[] = "Message";

  MPI_func(msg, length);
}
Multiple definition error upon including headers( How to add header in c?)

Multiple definition error upon including headers( How to add header in c?)


By : A Andreyev
Date : March 29 2020, 07:55 AM
Any of those help You should not define a function in a .h file. The error is most likely the missing function prototype const char *get_filename_ext(const char *);
(edited following comment)
code :
  //mygost.h  looks this way

  #ifndef MYGOST_H_
  #define MYGOST_H_
  #include <stdint.h>


  extern uint8_t transl_table(uint8_t in, uint8_t n);
  extern const char *get_filename_ext(const char *filename); 

  #endif

  //mygost.c  looks this way

  #include "mygost.h"


  extern uint8_t transl_table(uint8_t in, uint8_t n) {
  return tbl[n][in];
  }

  extern const char *get_filename_ext(const char *filename) 
  {
    const char *dot = strrchr(filename, '.');
    if(!dot || dot == filename) return "";
    return dot + 1;
  }
Can a C implementation implicitly include standard headers when including a different header?

Can a C implementation implicitly include standard headers when including a different header?


By : Tauhidtonmoy
Date : March 29 2020, 07:55 AM
Hope that helps C standard headers can not include other headers. This is different from C++, where it is explicitly allowed.
C99 standard, section 7.1.3
Problem including base header in all child headers

Problem including base header in all child headers


By : lindseyemaddox
Date : March 29 2020, 07:55 AM
With these it helps According to this answer #pragma once has unfixable bugs. It should never be used.
You can use header guards like below
code :
#ifndef HEADER_H
#define HEADER_H

// Header file code

#endif
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