[Bug libstdc++/46906] New: istreambuf_iterator is late?
marc.glisse at normalesup dot org
gcc-bugzilla@gcc.gnu.org
Sun Dec 12 15:26:00 GMT 2010
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46906
Summary: istreambuf_iterator is late?
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: marc.glisse@normalesup.org
The following program prints:
11
12
32
With some other libraries I get 11 22 33 (but libstdc++ is not the only one
that outputs 11 12 32).
As far as I understand the standard, operator++ and operator* should just call
sbumpc and sgetc on the underlying streambuf, which happens to be the same for
the two iterators. It looks like the iterator caches the result somehow. Am I
missing some provision for this in the standard?
#include <ios>
#include <istream>
#include <sstream>
#include <iostream>
using namespace std;
int main(){
istringstream s("1234");
istreambuf_iterator<char> i1(s);
istreambuf_iterator<char> i2(i1);
std::cerr << *i1 << *i2 << '\n';
++i2;
std::cerr << *i1 << *i2 << '\n';
++i1;
std::cerr << *i1 << *i2 << '\n';
}
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