Error when compiling cpp file with g++

Question

I have a CentOS 7 install running GCC 4.8.5 and I can successfully compile a cpp file named MyClass. I use the following command to compile the file:

g++ -c -fpermissive  $(pkg-config --cflags --libs libavformat libavcodec libswscale libavutil) ./MyClass.cpp

When I run this command on a Centos 6.7 running GCC 4.4.7, I get the following error:

In file included from ./MyClass.cpp:9:
./MyClass.h:70: warning: ISO C++ forbids initialization of member ‘pFormatCtx’
./MyClass.h:70: warning: making ‘pFormatCtx’ static
./MyClass.h:70: error: invalid in-class initialization of static data member of non-integral type ‘AVFormatContext*’

In my MyClass.h file, I have a private variable:

AVFormatContext   *pFormatCtx = NULL;

This error is repeated for any of the private variables that I initialize to NULL.

Is there an explanation for the difference I am encountering between my two CentOS installs?

This is the complete class:

    //
//  MyClass.h
//  FFMpegPlayground
//

#ifndef __FFMpegPlayground__MyClass__
#define __FFMpegPlayground__MyClass__

#include <stdio.h>

#ifndef INT64_C
#define INT64_C(c) (c ## LL)
#define UINT64_C(c) (c ## ULL)
#endif

#ifdef __cplusplus
#define __STDINT_MACROS
#endif

extern "C" {
#include <libavformat/avformat.h>
#include <libavcodec/avcodec.h>
#include <libswscale/swscale.h>
#include <libavutil/frame.h>
}

typedef enum {
    K_STATUS_OK = 0,
    K_CANT_OPEN_FILE = -1,
    K_NO_STREAM_INFO = -2,
    K_NO_VIDEO_STREAM = -3,
    K_CODEC_UNSUPPORTED = -4,
    K_CANT_COPY_CODEC = -5,
    K_CANT_OPEN_CODEC = -6,
    K_CANT_ALLOCATE_FRAME = -7,
    K_SEEK_FAILED = -8,
    K_UNABLE_TO_ACQUIRE_FRAME = -9
} MyClassStatus;

class MyClass{
public:
    MyClass();
    MyClass(const char * filePath);
    MyClass(const char * filePath, double nScale);
    ~MyClass();

    MyClassStatus getStatus();
    void seekToFrame(int frame);
    uint8_t* frameData();
    uint8_t* nextFrameData();
    uint8_t* copyOfNextFrameData();
    int getFrameHeight();
    int getFrameWidth();
    int getCurrentFrame();
    int getFrameDataSize();
    long long getNumberOfFrames();

private:

    bool fileIsLoaded;
    uint8_t* createFrame();
    int currentFrame;

    void internalSeekToFrame(int frame);

    MyClassStatus status;
    AVFormatContext   *pFormatCtx = NULL;
    int               i, videoStream;
    AVCodecContext    *pCodecCtxOrig = NULL;
    AVCodecContext    *pCodecCtx = NULL;
    AVCodec           *pCodec = NULL;
    AVFrame           *pFrame = NULL;
    AVFrame           *pFrameRGB = NULL;
    int               numBytes;
    uint8_t           *buffer = NULL;
    struct SwsContext *sws_ctx = NULL;
    uint8_t           *_createdFrameData = NULL;


    double preferredScale = 1.0;
};

#endif /* defined(__FFMpegPlayground__MyClass__) */

I think you should post more of your code. Somewhere you declare the variable as a static variable — Dave
– Dave, Commented Jan 27, 2016 at 21:16
I am not compiling for production, just testing my library linking. Otheriwse, yes, I would use -Wall — kernelK
– kernelK, Commented Jan 27, 2016 at 21:24
I'll be that guy: GCC 4.4.7 is a 4 year old minor version of a 7 year old branch. There has been a lot of progress in both compilers and the C++ spec since then. I know it's hard to get an organization to update, and even harder to get recent compilers on CentOS, but you yourself point out that this problem only exists on the ancient compiler. Just update. — Adam
– Adam, Commented Jan 27, 2016 at 21:25
Names that contain two consecutive underscores (__FFMpegPlayground__MyClass__) and names that begin with an underscore followed by a capital letter are reserved to the implementation. Don't use them. — Pete Becker
– Pete Becker, Commented Jan 27, 2016 at 22:07

Baum mit Augen · Accepted Answer · 2016-01-27 21:23:37Z

2

In-class initializers for non-static members like

AVFormatContext   *pFormatCtx = NULL;

are a C++11 feature. gcc4.4 is too old for that.

answered Jan 27, 2016 at 21:23

Baum mit Augen♦

50.4k25 gold badges153 silver badges187 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

kernelK Over a year ago

Ok, so I should move my initialization into my constructor then?

Baum mit Augen Over a year ago

@kernelK Either that, or use a newer compiler.

kernelK Over a year ago

Ok, this is a link to getting a newer GCC up and running on CentOS 6 superuser.com/questions/381160/…

Collectives™ on Stack Overflow

Error when compiling cpp file with g++

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related