GetSystemDirectory function (Windows API)

Retrieves the path of the system directory. The system directory contains system files such as dynamic-link libraries (DLLs) and executables that are essential to the OS.

Syntax

UINT WINAPI GetSystemDirectory(
    _Out_ LPTSTR lpBuffer,
    _In_  UINT   uSize
);

Parameters

Parameter	Type	Description
lpBuffer	LPTSTR	Pointer to a buffer that receives the system directory path.
uSize	UINT	Size of the buffer, in TCHARs.

Return value

If the function succeeds, the return value is the length of the string copied to lpBuffer, not including the terminating null character.

If the buffer is too small, the return value is the required size, in characters, for the buffer, including the terminating null character. In this case, the contents of lpBuffer are undefined.

If the function fails, the return value is zero. Use GetLastError for extended error information.

Remarks

The function does not guarantee that the path ends with a backslash.
On Windows XP and later, the system directory is C:\Windows\System32 for 32‑bit processes and C:\Windows\SysWOW64 for 64‑bit processes running under WOW64.
To retrieve the path of the Windows directory, use GetWindowsDirectory.

Example

#include <windows.h>
#include <stdio.h>

int main(void)
{
    TCHAR szPath[MAX_PATH];
    UINT len = GetSystemDirectory(szPath, MAX_PATH);
    if (len == 0 || len > MAX_PATH) {
        printf("Failed to get system directory. Error: %lu\n", GetLastError());
        return 1;
    }
    printf("System Directory: %s\n", szPath);
    return 0;
}

Output (example):
System Directory: C:\Windows\System32

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