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 Ampersand in Origin C		  New Topic  Reply to Topic
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peter.cook

UK
356 Posts
Posted - 01/28/2004 :  2:39:13 PM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Hi,

Can someone please enlighten me as to the purpose/function of the ampersand prefixing variables required in eg lt_get_var.

Cheers,

Pete

cpyang

USA
1406 Posts
Posted - 01/28/2004 :  11:16:00 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
That was because LT_get_var was prototyped as

LT_get_var(LPCSTR lpcszLabTalkVarName, double * lpdbResult);

so a pointer must be used to call this function.

Many other functions in Origin C use reference passing so that you don't need to use &myVal etc. Functions like LT_get_var are external functions in a DLL. When calling external functions, C calling must be used, and passing by reference is not supported in C, it is rather a C++ feature.


CP
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