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| Code Block | ||||
|---|---|---|---|---|
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#include <functional>
#include <iostream>
template <typename Ty>
bool in_range(const Ty *test, const Ty *r, size_t n) {
std::less<const Ty *> less;
return !less(test, r) && less(test, r + n);
}
void f() {
double foo[10];
double *x = &foo[0];
double bar;
std::cout << std::boolalpha << in_range(&bar, x, 10);
} |
Compliant Solution
There is no standard way to efficiently and portably determine if a pointer or iterator lives within a valid range.
In this compliant solution, a fully portable but likely inefficient equality comparing This compliant solution demonstrates a fully-portable, but likely inefficient, implementation of in_range() which compares test against each possible address in the range [r, n] is used to implement the in_range() function:.
| Code Block | ||||
|---|---|---|---|---|
| ||||
#include <iostream>
template <typename Ty>
bool in_range(const Ty *test, const Ty *r, size_t n) {
auto *cur = reinterpret_cast<const unsigned char *>(r);
auto *end = reinterpret_cast<const unsigned char *>(r + n);
auto *testPtr = reinterpret_cast<const unsigned char *>(test);
for (; cur != end; ++cur) {
if (cur == testPtr) {
return true;
}
}
return false;
}
void f() {
double foo[10];
double *x = &foo[0];
double bar;
std::cout << std::boolalpha << in_range(&bar, x, 10);
}
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