Dear all,
After sorting a vector, how to get max in this vector?
I got a strange result of my test code.
-------------------------------------------------
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main()
{
vector<int> vec;
vec.push_back(5);
vec.push_back(-5);
vec.push_back(10);
sort(vec.begin(),vec.end());
for (int i=0;i<vec.size();++i) {
cout << vec[i] << '\t';
}
cout << endl;
cout << "Max=" << *vec.end() << endl;
cout << "Min=" << vec[0] << endl;
cout << "Max=" << vec[vec.size()] << endl;
cout << endl;
return 0;
}
-------------------------------------------
The max should be 10.
But this program's result is -842150451.
What's wrong?
Thanks for your help.
Regards,
cylin. 3 4601
cylin wrote: Dear all,
After sorting a vector, how to get max in this vector? I got a strange result of my test code. ------------------------------------------------- #include <iostream> #include <vector> #include <algorithm> using namespace std;
int main() { vector<int> vec; vec.push_back(5); vec.push_back(-5); vec.push_back(10); sort(vec.begin(),vec.end()); for (int i=0;i<vec.size();++i) { cout << vec[i] << '\t'; } cout << endl; cout << "Max=" << *vec.end() << endl;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
vec.end() points to one beyond the end of the array.
*( vec.end() -1 )
cout << "Min=" << vec[0] << endl; cout << "Max=" << vec[vec.size()] << endl;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
vec[vec.size()] is undefined.
vec[vec.size()-1] is probably what you want.
cout << endl; return 0; } ------------------------------------------- The max should be 10. But this program's result is -842150451. What's wrong? Thanks for your help.
Regards, cylin.
Thanks............
I forgot the index is out of range.
Regards,
cylin.
"Gianni Mariani" <gi*******@mariani.ws>
???????:br********@dispatch.concentric.net...
cylin wrote: Dear all,
After sorting a vector, how to get max in this vector? I got a strange result of my test code. ------------------------------------------------- #include <iostream> #include <vector> #include <algorithm> using namespace std;
int main() { vector<int> vec; vec.push_back(5); vec.push_back(-5); vec.push_back(10); sort(vec.begin(),vec.end()); for (int i=0;i<vec.size();++i) { cout << vec[i] << '\t'; } cout << endl; cout << "Max=" << *vec.end() << endl;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
vec.end() points to one beyond the end of the array.
*( vec.end() -1 )
cout << "Min=" << vec[0] << endl; cout << "Max=" << vec[vec.size()] << endl;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
vec[vec.size()] is undefined.
vec[vec.size()-1] is probably what you want.
cout << endl; return 0; } ------------------------------------------- The max should be 10. But this program's result is -842150451. What's wrong? Thanks for your help.
Regards, cylin.
"cylin" <cy***@avant.com.tw> wrote in message
news:br************@ID-154203.news.uni-berlin.de... Thanks............ I forgot the index is out of range.
Regards, cylin. "Gianni Mariani" <gi*******@mariani.ws> ???????:br********@dispatch.concentric.net... cylin wrote: Dear all,
After sorting a vector, how to get max in this vector? I got a strange result of my test code. ------------------------------------------------- #include <iostream> #include <vector> #include <algorithm> using namespace std;
int main() { vector<int> vec; vec.push_back(5); vec.push_back(-5); vec.push_back(10); sort(vec.begin(),vec.end()); for (int i=0;i<vec.size();++i) { cout << vec[i] << '\t'; } cout << endl; cout << "Max=" << *vec.end() << endl; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
vec.end() points to one beyond the end of the array.
*( vec.end() -1 )
cout << "Min=" << vec[0] << endl; cout << "Max=" << vec[vec.size()] << endl; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ vec[vec.size()] is undefined.
vec[vec.size()-1] is probably what you want.
cout << endl; return 0; } ------------------------------------------- The max should be 10. But this program's result is -842150451. What's wrong? Thanks for your help.
Regards, cylin.
Even easier, I think:
vec.front() for the first element (a reference, not an iterator) and
vec.back() for the last one (again a reference). Hence:
cout << "Min=" << vec.front() << endl;
cout << "Max=" << vec.back() << endl;
Easier to read and less prone to errors IMHO.
--
Cy http://home.rochester.rr.com/cyhome/ This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
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