"warning: assignment makes integer from pointer without a cast" in C

christyyim · 12-23-2008, 09:29 AM

Here is the code I wrote to detect whether a LAN cable is pluged or unpluged. After compilation, it gives me the warning:

Quote:

warning: assignment makes integer from pointer without a cast

Here is my code:

PHP Code:



#include <stdio.h> 
#include <stdlib.h> 
#include <string.h> 
 
#define yes 1 
#define no 0 
typedef int boolean;  
 
int main() 
{ 
  FILE *fp; 
  char *pch; 
  char line[130];            /* line of easa!from unix command*/ 
  int m; 
  boolean b; 
    
  fp = popen("nm-tool | grep Link", "r");        /* Issue the command.        */ 
 
                    /* Read a line            */ 
  while ( fgets( line, sizeof line, fp)) 
  { 
    printf("%s", line); 
  } 
  pclose(fp); 
 
  pch = strtok (line,"     "); 
  for (m=0; m<2; m++) 
  { 
    pch = strtok (NULL, "     "); 
  } 
    printf ("%s\n",pch); 
  b = pch; 
  printf("%d\n",b);        /* more to add on */ 
 
  return 0; 
}

I have googled some solutions online, like include the stdlib.h header and etc but all didn't work. Does anyone has any idea on it?

Thanks in advance.

cmnorton · 12-23-2008, 09:57 AM

I am assuming this line is the offending line:

while ( fgets( line, sizeof line, fp))

fgets returns a char pointer. Either cast the result to an integer, ignore the warning, or rewrite to assign fgets to a pointer variable and test that.

Hko · 12-23-2008, 10:02 AM

The error is in the line:

Code:

b = pch;

'b' is and int, and 'p' is pointer to char. That is not correct syntax.

Assuming you are trying to have 'b' set to indicate whether 'pch' is a NULL pointer, you should change the line to:

Code:

b = (NULL==pch);

I wonder though why you are implementing a shell script in C....

swodniw · 12-23-2008, 10:13 AM

Quote:

Originally Posted by Hko

The error is in the line:

Code:

b = pch;

'b' is and int, and 'p' is pointer to char. That is not correct syntax.

Assuming you are trying to have 'b' set to indicate whether 'pch' is a NULL pointer, you should change the line to:

Code:

b = (NULL==pch);

I wonder though why you are implementing a shell script in C....

There is a typo there which would result in the incorrect behaviour. A number of options are available here.

Code:

 b = pch?1:0; b = pch!=NULL;/*Hko's fixed*/ b = !!pch;

christyyim · 12-23-2008, 11:42 AM

First of all, thanks for the replies from you all. And I just found out that I had misunderstood the way how strtok works and cause me write this program which may sound stupid to you all. hehe..

And now i'll rewrite the program again. Thanks for help.

Quote:

Originally Posted by Hko

I wonder though why you are implementing a shell script in C....

The reason I implement a shell script in C because this is the only way I found out so far which will let me know whether the LAN cable is plugged or unplugged. Or does anyone has any advice for me? Thanks.