Initializing a character array

Depends what you want to do. Generally, you can simply set the first character of each string in the array to '\0'. That's sufficient for most purposes.

Call memset() in the class instantiator (initialization code).


Kent

You can use either strcpy or memcpy or bzero or something like
char arr[10] = { 0 };

Since here you are only writing a single character, you could have as well used
for ( size_t i=0; i < MAX_NUM_LOG_MSGS; i++){
            this->mc_log_entries[i]= '\0';
      }

This will save you some CPU cycles but beware - only the first char has been set to 0

>>>> This will save you some CPU cycles but beware - only the first char has been set to 0

Hmmm. If you would do:


char mc_log_entries[MAX_NUM_LOG_MSGS][MAX_LOG_MSG_LEN] = { 0 };

the whole 2d array (all characters) would be all zeros. You don't need a memset nor a loop, at least not for initializing.

>> char mc_log_entries[MAX_NUM_LOG_MSGS][MAX_LOG_MSG_LEN] = { 0 };


I don't think so.  The array is defined within a class.  The initialization needs to occur at instantiation.


Kent

>> This will save you some CPU cycles but beware - only the first char has been set to 0

Yes, but that's generally sufficient as I said earlier. And since this is for embedded systems, it's nice to have every little speed gain heh :)

>>>> I don't think so.  The array is defined within a class.  The initialization needs to occur at instantiation.

Yes, I missed that. But maybe the array can be made a static member. Then initialization would be

   
 char MyOleClass::mc_log_entries[MAX_NUM_LOG_MSGS][MAX_LOG_MSG_LEN] = { 0 };

Note, big array members are only needed if the same array was used in different member functions. If it was used in one member function only it is better to use a local - maybe static - array.

All,

Thanks for the replies.

The array is used by most of the member functions so I'd rather not go static and can't be a local.

Even though it's an embedded system, CPU is not really an issue and the array is only about 500 x 500.

I'm leaning toward the memset method. Is there an advantage or disadvantage to filling the memory area with NULLs?

memset(mc_log_entries, '\0', MAX_NUM_LOG_MSGS * MAX_LOG_MSG_LEN * sizeof(char));

Thanks.

I can't see any disadvantages. It effectively initialies that to an array of empty strings.

If you are happy with just one memory allocation then how about using a pointer and calloc.

Paul

Regarding the use of memset() why not just:

memset(log_entries, '\0', sizeof(log_entries));

???