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In this example, a volatile object is accessed through a non-volatile-qualified reference, resulting in undefined behavior.
| Code Block | ||||
|---|---|---|---|---|
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static volatile int **ipp;
static int *ip;
static volatile int i = 0;
printf("i = %d.\n", i);
ipp = &ip; /* produces warnings in modern compilers */
ipp = (int**) &ip; /* constraint violation, also produces warnings */
*ipp = &i; /* valid */
if (*ip != 0) { /* valid */
/* ... */
}
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In this compliant solution, ip is declared volatile.
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static volatile int **ipp;
static volatile int *ip;
static volatile int i = 0;
printf("i = %d.\n", i);
ipp = &ip;
*ipp = &i;
if (*ip != 0) {
/* ... */
}
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