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From:Teresa A Narvaez Date:December 23 2004 6:14pm
Subject:Re: mysql_fetch_lengths()
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Thank you for the response.  I completely agree with your response.  The
reason why I asked this question is because I remember seeing len(unsigned
long *lengths;) dynamically allocated in the MYSQL manual some time
ago(when I was running mysql 3.23.30).  So, I wonder if there was a change
in the return value of mysql_fetch_lenghts() in mysql 3.23.58.
Otherwise, I made a mistake in dynamically allocating memory for len.  I
must have misunderstood.

Thank you.
-Teresa


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                      Dan Nelson                                                          
                   
                      <dnelson                 To:      Teresa A Narvaez/FED/CSC@CSC   
                      
                      @allantgroup.com         cc:      mysql@stripped             
                   
                      >                        Subject: Re: mysql_fetch_lengths()      
                      
                                                                                          
                   
                      12/23/2004 12:19                                                    
                   
                      PM                                                                  
                   
                                                                                          
                   
                                                                                          
                   




In the last episode (Dec 23), Teresa A Narvaez said:
> We were running mysql 3.22.30 on an Tru 64 Alpha server OSF 4.0F.  We
> recently upgraded to mysql 3.23.58 on the same server.
>
> In the code fragment below, there is a memory leak at line 8 because
> mysql_fetch_lenghts returns an array of unsigned long integers
> representing the size of each column.  So, has the retun value of
> mysql_fetch_lengths() been the same for mysql 3.22.30 and 3.23.58?
>
> 1. unsigned long *lengths;
> 2. unsigned int num_fields;
> 3. unsigned int i;
> 4. MYSQL_RES *result=NULL;
> 5. row = mysql_fetch_row(result);
> 6. if (row)
> 7. {
> 8.     len = malloc(sizeof(unsigned long) * mysql_num_fields(result));
> 9.     num_fields = mysql_num_fields(result);
> 10.    lengths = mysql_fetch_lengths(result);
> 11.    for(i = 0; i < num_fields; i++)
> 12.    {
> 13.         printf("Column %u is %lu bytes in length.\n", i, lengths[i]);
> 14.    }
> 15.    free(len)
> 16.}

The memory allocated at line 8 is freed at line 15.  In fact, it's
never used at all.  The array returned by mysql_fetch_lengths is an
internal array that is freed by mysql_free_result(); you don't need to
allocate it or free it.

--
             Dan Nelson
             dnelson@stripped

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Thread
mysql_fetch_lengths()Teresa A Narvaez23 Dec
  • Re: mysql_fetch_lengths()Dan Nelson23 Dec
Re: mysql_fetch_lengths()Teresa A Narvaez23 Dec
  • Re: mysql_fetch_lengths()Dan Nelson23 Dec
Re: mysql_fetch_lengths()Teresa A Narvaez23 Dec