GetTabbedTextExtentA function (winuser.h)

The GetTabbedTextExtent function computes the width and height of a character string. If the string contains one or more tab characters, the width of the string is based upon the specified tab stops. The GetTabbedTextExtent function uses the currently selected font to compute the dimensions of the string.


DWORD GetTabbedTextExtentA(
  [in] HDC       hdc,
  [in] LPCSTR    lpString,
  [in] int       chCount,
  [in] int       nTabPositions,
  [in] const INT *lpnTabStopPositions


[in] hdc

A handle to the device context.

[in] lpString

A pointer to a character string.

[in] chCount

The length of the text string. For the ANSI function it is a BYTE count and for the Unicode function it is a WORD count. Note that for the ANSI function, characters in SBCS code pages take one byte each, while most characters in DBCS code pages take two bytes; for the Unicode function, most currently defined Unicode characters (those in the Basic Multilingual Plane (BMP)) are one WORD while Unicode surrogates are two WORDs.

[in] nTabPositions

The number of tab-stop positions in the array pointed to by the lpnTabStopPositions parameter.

[in] lpnTabStopPositions

A pointer to an array containing the tab-stop positions, in device units. The tab stops must be sorted in increasing order; the smallest x-value should be the first item in the array.

Return value

If the function succeeds, the return value is the dimensions of the string in logical units. The height is in the high-order word and the width is in the low-order word.

If the function fails, the return value is 0. GetTabbedTextExtent will fail if hDC is invalid and if nTabPositions is less than 0.


The current clipping region does not affect the width and height returned by the GetTabbedTextExtent function.

Because some devices do not place characters in regular cell arrays (that is, they kern the characters), the sum of the extents of the characters in a string may not be equal to the extent of the string.

If the nTabPositions parameter is zero and the lpnTabStopPositions parameter is NULL, tabs are expanded to eight times the average character width.

If nTabPositions is 1, the tab stops are separated by the distance specified by the first value in the array to which lpnTabStopPositions points.


The winuser.h header defines GetTabbedTextExtent as an alias which automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.


Requirement Value
Minimum supported client Windows 2000 Professional [desktop apps only]
Minimum supported server Windows 2000 Server [desktop apps only]
Target Platform Windows
Header winuser.h (include Windows.h)
Library User32.lib
DLL User32.dll

See also

Font and Text Functions

Fonts and Text Overview