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struct and member function pointer

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Join Date: Apr 2006

Posts: 1

Reputation: Rass Saee is an unknown quantity at this point

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Rass Saee

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Newbie Poster

struct and member function pointer

Apr 26th, 2006

Does anybody know how member of function can be a pointer to a function. The following example crashes when I call the member that is pointing to a function.

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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <windows.h>
typedef long fooPtr(char *);
typedef struct
{
   fooPtr *func;
   long cnt;
} MyStruct;
/******************************************************************************/
long func(char * str)
{
   printf("%s\n", str);
   return -1;
}
/******************************************************************************/
void main(int argc, char *argv[])
{
   MyStruct *ex;
   long l = 0;
 
   ex = (MyStruct *)malloc(sizeof(MyStruct));
   if ( ex == NULL )
      printf("malloc failed");
   ex->cnt = 99;
   l = ex->func("Hello"); // crashes here
 
   free(ex);
   return;
}
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <windows.h>
typedef long fooPtr(char *);
typedef struct
{
   fooPtr *func;
   long cnt;
} MyStruct;
/******************************************************************************/
long func(char * str)
{
   printf("%s\n", str);
   return -1;
}
/******************************************************************************/
void main(int argc, char *argv[])
{
   MyStruct *ex;
   long l = 0;

   ex = (MyStruct *)malloc(sizeof(MyStruct));
   if ( ex == NULL )
      printf("malloc failed");
   ex->cnt = 99;
   l = ex->func("Hello"); // crashes here

   free(ex);
   return;
}

Thanks
Rass

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Join Date: Apr 2004

Posts: 4,452

Reputation: Dave Sinkula has a brilliant future

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Dave Sinkula Dave Sinkula is offline

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long time no c

Re: struct and member function pointer

Apr 26th, 2006

•

Originally Posted by Rass Saee

The following example crashes when I call the member that is pointing to a function.

You don't call a member function because you have not yet assigned one.

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(Toggle Plain Text)

#include <stdio.h>
#include <stdlib.h>

typedef long fooPtr(char *);
typedef struct
{
   fooPtr *func;
   long cnt;
} MyStruct;
/******************************************************************************/
long func(char * str)
{
   printf("%s\n", str);
   return -1;
}
/******************************************************************************/
int main(void)
{
   long l = 0;
   MyStruct *ex = malloc(sizeof *ex);
   if ( ex != NULL )
   {
      ex->func = func;
      ex->cnt = 99;
      l = ex->func("Hello"); // crashes here
      free(ex);
   }
   return 0;
}

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