Re: error C2678 and C2440

[Peter Slacik <peter dot slacik at tatramed dot sk>]

Hi,

(shortened)

satish wrote:
> Hi,
> I am porting my multi threading(using pthread) Linux project to
> windows. The compiler is MS VC++ 2005.
>
> The project compilation is almost done but I am  getting few errors
> related to pthread.
>
> A.:- Have a look on following code,
> ----------------------------------------------------------------
> typedef struct {
> 	pthread_t id;
> } THREADLIST;
>
> THREADLIST threads[MAXTHREADS];
>
> 1283	pthread_t self = pthread_self();
> 1286		if (threads[i].flags != THREAD_UNUSED && threads[i].id == self)			----------------------------------------------------------------
>
> The error, I am getting is,
>
> 1>main.cpp(1286) : error C2678: binary '==' : no operator found which
> takes a left-hand operand of type 'pthread_t' (or there is no
> acceptable conversion)
> 1> c:\program files\microsoft visual studio
> 8\vc\platformsdk\include\guiddef.h(192): could be 'int operator
> ==(const GUID &,const GUID &)'
> 1> while trying to match the argument list '(pthread_t, pthread_t)'
>
>   
IIRC you've to use int pthread_equal(pthread_t thread1, pthread_t
thread2) for the comparison. Because pthread_t is defined as:

     typedef struct {
         void * p;                   /* Pointer to actual object */
         unsigned int x;             /* Extra information - reuse count etc */
     } ptw32_handle_t;
     
     typedef ptw32_handle_t pthread_t;


> B.:- Another piece of code on which I am getting error is,
> ----------------------------------------------------------------
> 52    int ret;
> 53	ret = pthread_self();
> ----------------------------------------------------------------
> Here, it gives error like,
>
> 1>main.cpp(53) : error C2440: '=' : cannot convert from 'pthread_t' to 'int'
>
>   
Because of pthread_self()'s return value definition:

    pthread_t pthread_self (void);

Already in your previous example, you've used

    1283	pthread_t self = pthread_self();
      

This is the way to go.

> Can you please tell me the reason behind these errors?
> I will be very thankful to you.
>
> Regards
> Satish
>   

With regards
Peter

PS: I'm resending this, my original email was not plain text, sorry.