c26101.md

description	title	ms.date	f1_keywords	helpviewer_keywords	ms.assetid
Learn more about: Warning C26101	Warning C26101	11/04/2016	C26101	C26101	86046553-09ec-40ce-82b3-fd641928f0b0

Warning C26101

Failing to use interlocked operation properly for variable 'var'.

Windows APIs offer various interlocked operations. Annotation _Interlocked_ specifies that a variable should only be accessed through an interlocked operation. Warning C26101 is issued when a variable access isn't consistent with the _Interlocked_ annotation.

Example

The following example generates warning C26101 because there's a violation of the _Interlocked_ contract.

CRITICAL_SECTION cs;
typedef struct _DATA
{
    _Interlocked_ LONG data;
} DATA;

void Safe(DATA* p)
{
    InterlockedIncrement(&p->data); // OK
}

void Unsafe(DATA* p)
{
    p->data += 1; // Warning C26101
    EnterCriticalSection(&cs);
    LeaveCriticalSection(&cs);
}