Rewrote iota_n to use pre-increment instead of post - now the same as iota. Added a test for 0 as well.

mclow · mclow · commit fe51eb60a922 · 2013-08-25T16:29:01.000Z
[SVN r85465]
diff --git a/include/boost/algorithm/cxx11/iota.hpp b/include/boost/algorithm/cxx11/iota.hpp
@@ -63,8 +63,8 @@ void iota ( Range &r, T value )
 template <typename OutputIterator, typename T>
 OutputIterator iota_n ( OutputIterator out, T value, std::size_t n )
 {
-    while ( n-- > 0 )
-        *out++ = value++;
+    for ( ; n > 0; --n, ++value )
+        *out++ = value;
 
     return out;
 }
diff --git a/test/iota_test1.cpp b/test/iota_test1.cpp
@@ -42,18 +42,22 @@ void test_ints () {
     std::vector<int> v;
     std::list<int> l;
 
-    v.clear (); v.reserve ( 10 );
+    v.clear (); v.resize ( 10 );
     boost::algorithm::iota ( v.begin (), v.end (), 23 );
     BOOST_CHECK ( test_iota_results ( v.begin (), v.end (), 23 ));
     
-    v.clear (); v.reserve ( 19 );
+    v.clear (); v.resize ( 19 );
     boost::algorithm::iota ( v, 18 );
     BOOST_CHECK ( test_iota_results ( v, 18 ));
     
     v.clear ();
     boost::algorithm::iota_n ( std::back_inserter(v), 99, 20 );
     BOOST_CHECK ( test_iota_results ( v, 99 ));
     
+    v.clear ();
+    boost::algorithm::iota_n ( std::back_inserter(v), 99, 0 );
+    BOOST_CHECK ( v.size() == 0 );
+
 /*
     l.clear (); l.reserve ( 5 );
     boost::algorithm::iota ( l.begin (), l.end (), 123 );

Original file line number	Diff line number	Diff line change
`@@ -63,8 +63,8 @@ void iota ( Range &r, T value )`
`63`	`63`	`template <typename OutputIterator, typename T>`
`64`	`64`	`OutputIterator iota_n ( OutputIterator out, T value, std::size_t n )`
`65`	`65`	`{`
`66`		`- while ( n-- > 0 )`
`67`		`- *out++ = value++;`
	`66`	`+ for ( ; n > 0; --n, ++value )`
	`67`	`+ *out++ = value;`
`68`	`68`
`69`	`69`	`return out;`
`70`	`70`	`}`