C: int to _bstr_t

Question

im trying to draw series of plots in excel using c. The problem is when i try to put making of plots in loop, i must change name of worksheets in excel. But those names are in _bstr_t format:

    pSheet->Name =name;

I want to make name look something like ("Sheet number %d",i), where i is counter. I tried using sprintf and may other methods but with no luck.

Any help would be appreciated!

I think you have to use the [BSTR functions](http://msdn.microsoft.com/en-us/library/windows/desktop/ms221069%28v=vs.85%29.aspx) to use BSTRs... — sarnold, Jun 12 '12 at 00:43

score 0 · Answer 1 · answered Jun 12 '12 at 03:42

0

First create a character array with the name and then assign it to Name.

char arr[25];
sprintf(arr, "Sheet number %d", i);
pSheet->Name = arr;

answered Jun 12 '12 at 03:42

Superman

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score 0 · Answer 2 · edited May 23 '17 at 12:03

The class _bstr_t is a C++ wrapper class around the BSTR datatype, which is defined as WCHAR *. See for example What's the difference between BSTR and _bstr_t?. If you are doing C, then your reference to _bstr_t is probably incorrect and you should be asking for a conversion to BSTR instead.

The following lines of code can do that for you:

DWORD len;
BSTR  bstrPtr;
char  sheetName[25];

/* Construct the name of your sheet as a regular string */
sprintf(sheetName, "Sheet number %d", i);
/* Count the number of bytes in the WChar version of your name
   by doing a dummy conversion */
len = MultiByteToWideChar(CP_ACP, 0, sheetName, -1, 0, 0);
/* Allocate the BSTR with this size */
bstrPtr = SysAllocStringLen(0, len);
/* Do the actual conversion of the sheetName into BSTR */
MultiByteToWideChar(CP_ACP, 0, sheetName, -1, bstrPtr, len);

/* Do your stuff... */

/* Deallocate the BSTR */
SysFreeString(bstrPtr);

If your reference to _bstr_t is correct and this code does not answer your question, then please post a snippet of the header files that you are using, showing the definition of the name attribute. Also, the statement pSheet->Name = name is not likely to set the name of an Excel sheet, since that typically involves invoking a function instead of plainly setting an attribute. Understanding that would require more context from you as well.

C: int to _bstr_t

2 Answers2