我的operator
在std::map内的Key中使用此包装器类时，如果我混合使用不同长度的数组，则无法在at / find调用函数。
const oid oid1[] = { 1,3,6,1,4,1,42570,1,3,1 };
oid_wrapper wrapper1(oid1, 10);
const oid oid2[] = { 1,3,6,1,4,1,42570,1,3,1,9,1 };
oid_wrapper wrapper1(oid2, 12);
当先将wrapper1然后再将wrapper2添加到映射中时，它将始终使用at / find查找wrapper1，但是对于wrapper2，它将在at和iterator.end上使用find找到一个out_of_range异常。
当先将wrapper2然后再将wrapper1添加到映射时，它将始终使用at / find查找wrapper2，但是对于wrapper1，它将在at和iterator.end上使用find查找抛出out_of_range异常。
类型oid来自Net-SNMP，实际上是一个无符号的long int。
那么我的实现遗漏了什么或做错了什么呢？
#include <ostream>
#include <sstream>
#include <net-snmp/net-snmp-config.h>
#include <net-snmp/net-snmp-includes.h>
class oid_wrapper {
public:
oid_wrapper(const oid* _oid_value, int _oid_length) : oid_value(0), oid_length (_oid_length) {
oid_value = snmp_duplicate_objid(_oid_value, oid_length);
}
const oid* get_oid() const { return oid_value; }
const int& get_length() const { return oid_length; }
/**
* copy operator overloader
*/
oid_wrapper& operator=(const oid_wrapper& wrapper) {
oid_value = snmp_duplicate_objid(wrapper.get_oid(), wrapper.get_length());
oid_length = wrapper.get_length();
return *this;
}
/**
* equal operator overloader
*/
bool operator==(const oid_wrapper& rhs) const {
const oid* rhs_oid = rhs.get_oid();
const int rhs_length = rhs.get_length();
if (netsnmp_oid_equals(oid_value, oid_length, rhs_oid, rhs_length) == 0) {
return true;
} else {
return false;
}
}
/**
* less-than operator overloader
*/
bool operator<(const oid_wrapper& rhs) const {
const oid* rhs_oid = rhs.get_oid();
const int rhs_length = rhs.get_length();
if (oid_length < rhs_length) { return true; }
for (int i = 0; i < oid_length; i++) {
if (oid_value[i] < rhs_oid[i]) { return true; }
}
return false;
}
const long getLastNumberInOid() const { return oid_value[oid_length - 1]; }
bool operator!=(const oid_wrapper& rhs) { return !operator==(rhs); }
bool operator>(const oid_wrapper& rhs) { return !operator<(rhs); }
bool operator<=(const oid_wrapper& rhs) { return !operator>(rhs); }
bool operator>=(const oid_wrapper& rhs) { return !operator<(rhs); }
private:
const oid* oid_value;
int oid_length;
};
这是我设计的测试类，旨在检查它是否有效:
#include <iostream>
#include <ostream>
#include <string>
#include <map>
#include <stdexcept>
#include <net-snmp/net-snmp-config.h>
#include <net-snmp/net-snmp-includes.h>
#include "oid_wrapper.h"
using namespace std;
int main(int argc, char **argv) {
cout << "Testing first set of OID" << endl;
const oid oid1[] = { 1,3,6,1,4,1,40850,1,3 };
const oid_wrapper parent1 (oid1, 9);
const oid_wrapper parent1_child1 (parent1, 40);
const oid_wrapper parent1_child2 (parent1, 41);
const oid_wrapper parent1_child3 (parent1, 42);
const oid_wrapper parent1_child4 (parent1, 43);
map<oid_wrapper, string> test;
test.insert(make_pair(parent1_child1, "parent1_child1"));
test.insert(make_pair(parent1_child2, "parent1_child2"));
test.insert(make_pair(parent1_child3, "parent1_child3"));
test.insert(make_pair(parent1_child4, "parent1_child4"));
if (test.size() != 4) { cout << "FAIL" << endl; }
cout << "Number of OID in list: " << test.size() << endl;
const oid_wrapper parent11 (oid1, 9);
const oid_wrapper parent1_child11 (parent11, 40);
try {
string teststring = test.at(parent1_child11);
cout << "Success" << endl;
} catch (out_of_range& e) {
cout << "Failure" << endl;
}
const oid_wrapper parent1_child12 (parent11, 41);
try {
string teststring = test.at(parent1_child12);
cout << "Success" << endl;
} catch (out_of_range& e) {
cout << "Failure" << endl;
}
const oid_wrapper parent1_child13 (parent11, 42);
try {
string teststring = test.at(parent1_child13);
cout << "Success" << endl;
} catch (out_of_range& e) {
cout << "Failure" << endl;
}
const oid_wrapper parent1_child14 (parent11, 43);
try {
string teststring = test.at(parent1_child14);
cout << "Success" << endl;
} catch (out_of_range& e) {
cout << "Failure" << endl;
}
cout << "Testing second set of OID" << endl;
const oid oid2[] = { 1,3,6,1,4,1,40850,2,1,9,1 };
const oid_wrapper parent2 (oid2, 11);
const oid_wrapper parent2_child1 (parent2, 1);
const oid_wrapper parent2_child2 (parent2, 2);
const oid_wrapper parent2_child3 (parent2, 3);
const oid_wrapper parent2_child4 (parent2, 4);
test.insert(make_pair(parent2_child1, "parent2_child1"));
test.insert(make_pair(parent2_child2, "parent2_child2"));
test.insert(make_pair(parent2_child3, "parent2_child3"));
test.insert(make_pair(parent2_child4, "parent2_child4"));
if (test.size() != 8) { cout << "FAIL" << endl; }
cout << "Number of OID in list: " << test.size() << endl;
const oid_wrapper parent21 (oid2, 11);
const oid_wrapper parent1_child21 (parent21, 1);
try {
string teststring = test.at(parent1_child21);
cout << "Success" << endl;
} catch (out_of_range& e) {
cout << "Failure" << endl;
}
const oid_wrapper parent1_child22 (parent21, 2);
try {
string teststring = test.at(parent1_child22);
cout << "Success" << endl;
} catch (out_of_range& e) {
cout << "Failure" << endl;
}
const oid_wrapper parent1_child23 (parent21, 3);
try {
string teststring = test.at(parent1_child23);
cout << "Success" << endl;
} catch (out_of_range& e) {
cout << "Failure" << endl;
}
const oid_wrapper parent1_child24 (parent21, 4);
try {
string teststring = test.at(parent1_child24);
cout << "Success" << endl;
} catch (out_of_range& e) {
cout << "Failure" << endl;
}
//#################################################
//Adding 100 OIDs
for (int i = 0; i < 100; i++) {
const oid newoid[] = { 1,3,6,1,4,1,40850,2,1,9,1 };
const oid_wrapper wrapper(newoid, 11, i);
test.insert(make_pair(wrapper, "wrapper"));
}
//Query for the 100 added OIDs
int run1 = 0;
for (int i = 0; i < 100; i++) {
const oid newoid[] = { 1,3,6,1,4,1,40850,2,1,9,1 };
const oid_wrapper wrapper(newoid, 11, i);
try {
string teststring = test.at(wrapper);
run1++;
} catch (out_of_range& e) {
//FAIL
}
}
if (run1 == 100) { cout << "Run 1 Success" << endl; }
else { cout << "Run 1: " << run1 << endl; }
//#################################################
//Adding 100 OIDs
for (int i = 0; i < 100; i++) {
const oid newoid[] = { 1,3,6,1,4,1,40850,1,3 };
const oid_wrapper wrapper(newoid, 9, i);
test.insert(make_pair(wrapper, "wrapper"));
}
//Query for the 100 added OIDs
int run2 = 0;
for (int i = 0; i < 100; i++) {
const oid newoid[] = { 1,3,6,1,4,1,40850,1,3 };
const oid_wrapper wrapper(newoid, 9, i);
try {
string teststring = test.at(wrapper);
run2++;
} catch (out_of_range& e) {
//FAIL
}
}
if (run2 == 100) { cout << "Run 2 Success" << endl; }
else { cout << "Run 2: " << run2 << endl; }
//#################################################
//Adding 100 OIDs
for (int i = 0; i < 10; i++) {
const oid newoid[] = { 1,3,6,1,4,1,40850,2 };
const oid_wrapper wrapper(newoid, 8, i);
test.insert(make_pair(wrapper, "wrapper"));
}
//Query for the 100 added OIDs
int run3 = 0;
for (int i = 0; i < 10; i++) {
const oid newoid[] = { 1,3,6,1,4,1,40850,2 };
const oid_wrapper wrapper(newoid, 8, i);
try {
string teststring = test.at(wrapper);
run3++;
} catch (out_of_range& e) {
//FAIL
}
}
if (run3 == 10) { cout << "Run 3 Success" << endl; }
else { cout << "Run 3: " << run3 << endl; }
//#################################################
//Adding 100 OIDs
for (int i = 0; i < 100; i++) {
const oid newoid[] = { 1,3,6,1,4,1,40850,2,2,5,1 };
const oid_wrapper wrapper(newoid, 11, i);
test.insert(make_pair(wrapper, "wrapper"));
}
//Query for the 100 added OIDs
int run4 = 0;
for (int i = 0; i < 100; i++) {
const oid newoid[] = { 1,3,6,1,4,1,40850,2,2,5,1 };
const oid_wrapper wrapper(newoid, 11, i);
try {
string teststring = test.at(wrapper);
run4++;
} catch (out_of_range& e) {
//FAIL
}
}
if (run4 == 100) { cout << "Run 4 Success" << endl; }
else { cout << "Run 4: " << run4 << endl; }
//#################################################
//Adding 100 OIDs
for (int i = 0; i < 100; i++) {
const oid newoid[] = { 1,3,6,1,4,1,40850,2,3,5,2 };
const oid_wrapper wrapper(newoid, 11, i);
test.insert(make_pair(wrapper, "wrapper"));
}
//Query for the 100 added OIDs
int run5 = 0;
for (int i = 0; i < 100; i++) {
const oid newoid[] = { 1,3,6,1,4,1,40850,2,3,5,2 };
const oid_wrapper wrapper(newoid, 11, i);
try {
string teststring = test.at(wrapper);
run5++;
} catch (out_of_range& e) {
//FAIL
}
}
if (run5 == 100) { cout << "Run 5 Success" << endl; }
else { cout << "Run 5: " << run5 << endl; }
//#################################################
//Adding 100 OIDs
for (int i = 0; i < 100; i++) {
const oid newoid[] = { 1,3,6,1,4,1,40850,2,2,5,2 };
const oid_wrapper wrapper(newoid, 10, i);
test.insert(make_pair(wrapper, "wrapper"));
}
//Query for the 100 added OIDs
int run6 = 0;
for (int i = 0; i < 100; i++) {
const oid newoid[] = { 1,3,6,1,4,1,40850,2,2,5,2 };
const oid_wrapper wrapper(newoid, 10, i);
try {
string teststring = test.at(wrapper);
run6++;
} catch (out_of_range& e) {
//FAIL
}
}
if (run6 == 100) { cout << "Run 6 Success" << endl; }
else { cout << "Run 6: " << run6 << endl; }
//#################################################
//Adding 100 OIDs
for (int i = 0; i < 100; i++) {
const oid newoid[] = { 1,3,6,1,4,1,40850,2,5,2,3,5 };
const oid_wrapper wrapper(newoid, 12, i);
test.insert(make_pair(wrapper, "wrapper"));
}
//Query for the 100 added OIDs
int run7 = 0;
for (int i = 0; i < 100; i++) {
const oid newoid[] = { 1,3,6,1,4,1,40850,2,5,2,3,5 };
const oid_wrapper wrapper(newoid, 12, i);
try {
string teststring = test.at(wrapper);
run7++;
} catch (out_of_range& e) {
//FAIL
}
}
if (run7 == 100) { cout << "Run 7 Success" << endl; }
else { cout << "Run 7: " << run7 << endl; }
}
最佳答案
问题可能是您的operator<不对称。想象一下这段代码:
const oid oid1[] = {5};
oid_wrapper wrapper1(oid1, 1);
const oid oid2[] = {1, 4};
oid_wrapper wrapper2(oid2, 2);
bool b1 = wrapper1 < wrapper2;
bool b2 = wrapper2 < wrapper1;
b1是true，因为wrapper1的长度小于wrapper2的长度。b2也是true，因为wrapper2中的第一个oid小于wrapper1中的第一个oid。您必须确保
operator<是整体订购。如果是false，则应返回oid_length > rhs_length。同样，您不能将
operator>实现为! <，因为这不适用于相等的值。对于操作员而言，最好的选择是实现operator==和operator<，并将其余部分表示为(伪代码):operator!=(a, b) {! (a == b)}
operator<=(a, b) {a < b || a == b}
operator>(a, b) {! (a < b)}
operator>=(a, b) {! (a < b)}
关于c++ - 重载运算符<用于长值数组，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/13452181/