>Thank-you for your explanation. As I was testing it I discovered basically what you described. So when the variable is used as an input I am using it without the "@" but when it is an output then I am adding the "@".
>
>Simon
>
Right

I believe - for input, without @ - vfp copies the whole string before passing it.

Basically I only use without @ for any of the conditions below

- i need to be able to pass a null pointer, ie null
- I use a string constant, ie no variable name


For input, and a variable, I use @


>>>Hi
>>>
>>>I would like to know the correct way to delcare the following C function in VFP:
>>>
>>>int SetServer_IP (int context, char *Value);
>>>
>>>I used:
>>>
>>>Declare Integer SetServer_IP In XTran.dll As PP_SetServer_IP Integer lnContext,String lcIP
>>>
>>>but I am wondering whether the it should be:
>>>
>>>Declare Integer SetServer_IP In XTran.dll As PP_SetServer_IP Integer lnContext,String @ lcIP
>>>
>>>Thanks,
>>>Simon
>>
>>Depends
>>
>>(1)
>>

>>Declare Integer SetServer_IP In XTran.dll As PP_SetServer_IP Integer lnContext,String lcIP
>>

>>
>>When calling
>>
>>The string lcIP cannot be changed by the api
>>The string variable is not preceded by @
>>

>>lcIP = 'something'
>> = SetServer_IP(123, m.lcIP)
>>

>>
>>You can pass null
>>

>> = SetServer_IP(123, null)
>>

>>
>>(2)
>>

>>Declare Integer SetServer_IP In XTran.dll As PP_SetServer_IP Integer lnContext,String @ lcIP
>>

>>The string lcIP can be changed by the api
>>The string variable is preceded by @
>>

>>lcIP = 'something'
>> = SetServer_IP(123, @m.lcIP)
>>

>>
>>Impossible to pass null