ReadConsoleOutput function
Important
This document describes console platform functionality that is no longer a part of our ecosystem roadmap. We do not recommend using this content in new products, but we will continue to support existing usages for the indefinite future. Our preferred modern solution focuses on virtual terminal sequences for maximum compatibility in cross-platform scenarios. You can find more information about this design decision in our classic console vs. virtual terminal document.
Reads character and color attribute data from a rectangular block of character cells in a console screen buffer, and the function writes the data to a rectangular block at a specified location in the destination buffer.
Syntax
BOOL WINAPI ReadConsoleOutput(
_In_ HANDLE hConsoleOutput,
_Out_ PCHAR_INFO lpBuffer,
_In_ COORD dwBufferSize,
_In_ COORD dwBufferCoord,
_Inout_ PSMALL_RECT lpReadRegion
);
Parameters
hConsoleOutput [in]
A handle to the console screen buffer. The handle must have the GENERIC_READ access right. For more information, see Console Buffer Security and Access Rights.
lpBuffer [out]
A pointer to a destination buffer that receives the data read from the console screen buffer. This pointer is treated as the origin of a two-dimensional array of CHAR_INFO structures whose size is specified by the dwBufferSize parameter.
dwBufferSize [in]
The size of the lpBuffer parameter, in character cells. The X member of the COORD structure is the number of columns; the Y member is the number of rows.
dwBufferCoord [in]
The coordinates of the upper-left cell in the lpBuffer parameter that receives the data read from the console screen buffer. The X member of the COORD structure is the column, and the Y member is the row.
lpReadRegion [in, out]
A pointer to a SMALL_RECT structure. On input, the structure members specify the upper-left and lower-right coordinates of the console screen buffer rectangle from which the function is to read. On output, the structure members specify the actual rectangle that was used.
Return value
If the function succeeds, the return value is nonzero.
If the function fails, the return value is zero. To get extended error information, call GetLastError.
Remarks
ReadConsoleOutput treats the console screen buffer and the destination buffer as two-dimensional arrays (columns and rows of character cells). The rectangle pointed to by the lpReadRegion parameter specifies the size and location of the block to be read from the console screen buffer. A destination rectangle of the same size is located with its upper-left cell at the coordinates of the dwBufferCoord parameter in the lpBuffer array. Data read from the cells in the console screen buffer source rectangle is copied to the corresponding cells in the destination buffer. If the corresponding cell is outside the boundaries of the destination buffer rectangle (whose dimensions are specified by the dwBufferSize parameter), the data is not copied.
Cells in the destination buffer corresponding to coordinates that are not within the boundaries of the console screen buffer are left unchanged. In other words, these are the cells for which no screen buffer data is available to be read.
Before ReadConsoleOutput returns, it sets the members of the structure pointed to by the lpReadRegion parameter to the actual screen buffer rectangle whose cells were copied into the destination buffer. This rectangle reflects the cells in the source rectangle for which there existed a corresponding cell in the destination buffer, because ReadConsoleOutput clips the dimensions of the source rectangle to fit the boundaries of the console screen buffer.
If the rectangle specified by lpReadRegion lies completely outside the boundaries of the console screen buffer, or if the corresponding rectangle is positioned completely outside the boundaries of the destination buffer, no data is copied. In this case, the function returns with the members of the structure pointed to by the lpReadRegion parameter set such that the Right member is less than the Left, or the Bottom member is less than the Top. To determine the size of the console screen buffer, use the GetConsoleScreenBufferInfo function.
The ReadConsoleOutput function has no effect on the console screen buffer's cursor position. The contents of the console screen buffer are not changed by the function.
This function uses either Unicode characters or 8-bit characters from the console's current code page. The console's code page defaults initially to the system's OEM code page. To change the console's code page, use the SetConsoleCP or SetConsoleOutputCP functions. Legacy consumers may also use the chcp or mode con cp select= commands, but it is not recommended for new development.
Tip
This API is not recommended and does not have a virtual terminal equivalent. This decision intentionally aligns the Windows platform with other operating systems where the individual client application is expected to remember its own drawn state for further manipulation. Applications remoting via cross-platform utilities and transports like SSH may not work as expected if using this API.
Examples
For an example, see Reading and Writing Blocks of Characters and Attributes.
Requirements
| Minimum supported client | Windows 2000 Professional [desktop apps only] |
| Minimum supported server | Windows 2000 Server [desktop apps only] |
| Header | ConsoleApi2.h (via WinCon.h, include Windows.h) |
| Library | Kernel32.lib |
| DLL | Kernel32.dll |
| Unicode and ANSI names | ReadConsoleOutputW (Unicode) and ReadConsoleOutputA (ANSI) |