...
| Code Block | ||||
|---|---|---|---|---|
| ||||
#include <cstring>
class C {
int *i;
public:
C() : i(nullptr) {}
~C() { delete i; }
void set(int val) {
if (i) { delete i; }
i = new int{val};
}
// ...
};
void f(C &c1) {
C c2;
std::memcpy(&c2, &c1, sizeof(C));
} |
...
| Code Block | ||||
|---|---|---|---|---|
| ||||
class C {
int *i;
public:
C() : i(nullptr) {}
~C() { delete i; }
void set(int val) {
if (i) { delete i; }
i = new int{val};
}
C &operator=(const C &rhs) noexcept(false) {
if (this != &rhs) {
int *o = nullptr;
if (rhs.i) {
o = new int;
*o = *rhs.i;
}
// Does not modify this unless allocation succeeds.
delete i;
i = o;
}
return *this;
}
// ...
};
void f(C &c1) {
C c2 = c1;
} |
...
| Code Block | ||||
|---|---|---|---|---|
| ||||
#include <cstring>
class C {
int i;
public:
virtual void f();
// ...
};
void f(C &c1, C &c2) {
if (!std::memcmp(&c1, &c2, sizeof(C))) {
// ...
}
} |
Because a vtable is not part of an object's value representation, comparing it with std::memcmp() is also a violation of EXP62-CPP. Do not access the bits of an object representation that are not part of the object's value representation.
Compliant Solution
In this compliant solution, C defines an equality operator that is used instead of calling std::memcmp(). This solution ensures that only the value representation of the objects is considered when performing the comparison.
...