Geomorphology and Auto ptr: Difference between pages

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{{wrongtitle|title=auto_ptr}}
[[Image:Earth surface NGDC 2000.jpg|thumb|Surface of the Earth]]
 
'''auto_ptr''' is a [[Template (programming) | template]] class available in the [[C_plus_plus|C++]] [[C Plus Plus standard library | Standard Library]] (declared in '''<memory>''') that provides some basic [[Resource Acquisition Is Initialization | RAII]] features for [[Pointers#C.2FC.2B.2B | C++ raw pointers]].
'''Geomorphology''' is the study of [[landforms]], including their origin and evolution, and the processes that shape them. The underlying question is: Why do landscapes look the way they do? The term is derived from the Greek ''geo'', meaning ''Earth'', and ''morph'', meaning form. Geomorphologists seek to understand landform history and dynamics, and predict future changes through a combination of field observation, physical experiment, and numerical modeling. The discipline is practiced within [[geology]], [[geography]], [[archaeology]] and [[civil engineering|civil]] and [[environmental engineering]].
 
== Definition ==
Landforms evolve in response to a combination of natural and anthropogenic processes. The landscape is built up through [[tectonic uplift]] and [[volcanism]]. Denudation occurs by [[erosion]] and [[mass wasting]], which produces sediment that is transported and [[deposition (geology)|deposited]] elsewhere within the landscape or off the coast. Landscapes are also lowered by subsidence, either due
to tectonics or physical changes in underlying sedimentary deposits. These processes are each influenced differently by [[climate]], [[ecology]], and human activity.
 
The auto_ptr class is defined in [[ISO/IEC 14882]], section 20.4.5 as:
Particular applications of geomorphology include landslide prediction and mitigation, river control and restoration, coastal protection, and even assessing the presence of water on [[Mars (planet)|Mars]].
 
namespace std {
template <class Y> struct auto_ptr_ref {};
template<class X>
class auto_ptr {
public:
typedef X element_type;
// 20.4.5.1 construct/copy/destroy:
explicit auto_ptr(X* p =0) throw();
auto_ptr(auto_ptr&) throw();
template<class Y> auto_ptr(auto_ptr<Y>&) throw();
auto_ptr& operator=(auto_ptr&) throw();
template<class Y> auto_ptr& operator=(auto_ptr<Y>&) throw();
auto_ptr& operator=(auto_ptr_ref<X> r) throw();
~auto_ptr() throw();
// 20.4.5.2 members:
X& operator*() const throw();
X* operator->() const throw();
X* get() const throw();
X* release() throw();
void reset(X* p =0) throw();
// 20.4.5.3 conversions:
auto_ptr(auto_ptr_ref<X>) throw();
template<class Y> operator auto_ptr_ref<Y>() throw();
template<class Y> operator auto_ptr<Y>() throw();
};
}
 
== History ==
 
== Semantics ==
Geomorphology was not originally differentiated from the rest of geology. The first geomorphic model was the "cycle of erosion", developed by [[William Morris Davis]] between [[1884]] and [[1899]]. The cycle was inspired by theories of [[evolution]], and was depicted as a sequence by which a river would cut a valley more and more deeply, but then erosion of side valleys would eventually flatten out the terrain again, now at a lower elevation. The cycle could be started over by [[uplift]] of the terrain. The model is today considered too much of a simplification to be especially useful in practice.
 
The auto_ptr has semantics of strict ownership, meaning that the auto_ptr instance is the sole responsible for the object's life-time. If an auto_ptr is copied, the source loses the reference. For example:
[[Walther Penck]] developed an alternative model in the [[1920s]], based on ratios of uplift and erosion, but it was also too weak to explain a variety of landforms.
 
int *i = new int;
== Processes ==
auto_ptr<int> x(i);
auto_ptr<int> y;
y = x;
cout << x.get() << endl;
cout << y.get() << endl;
 
This code will print a [[Null (Computer) | NULL]] reference for the first auto_ptr object and some address for the second, showing that the source object lost the reference during the assignment (''=''). The raw pointer ''i'' in the example should not be deleted, as it will be deleted by the auto_ptr that owns the reference.
[[Image:Earth_seafloor_crust_age_1996.gif|thumb|Age of seafloor crust. Red is youngest.]]
Modern geomorphology focuses on the quantitative analysis of interconnected processes, such as the contribution of [[solar energy]], the rates of steps of the [[hydrologic cycle]], and plate movement rates from [[geophysics]] to compute the age and expected fate of landforms. The use of more precise measurement technique has also enabled processes like erosion to be observed directly, rather than merely surmised from other evidence. Computer [[simulation]] is also valuable for testing that a particular model yields results with properties similar to real terrain.
 
Notice that the object pointed by an auto_ptr is destructed using ''operator delete''; this means that you should only use auto_ptr for pointers obtained with ''operator new''. This excludes pointers returned by [[malloc|malloc/calloc/realloc]] and ''operator new[]''.
Primary surface processes responsible for most topographic features include [[wind]], waves, weathering, mass wasting, ground water, surface water, [[glacier|glaciers]], tectonism, and volcanism.
 
=== Fluvial Geomorphology ===
 
{{uncategorized}}
Rivers and streams are not only conduits of water, but also of [[sediment]]. The water, as it flows over the channel bed, is able to mobilise sediment and transport it downstream, either as [[bedload]] or [[suspended load]]. The rate of sediment transport depends on the avilability of sediment itself and on the river's [[discharge]].
 
As rivers flow across the landscape, they generally increase in size, merging with other rivers. The network of rivers thus formed is a [[drainage system]] and is often dentritic, but may adopt other patterns depending on the regional topography and underlying geology.
 
=== Glacial Geomorphology ===
 
[[Glacier]]s, while geographically restricted, are effective agents of landscape change. The gradual movement of [[ice]] down a valley causes [[abrasion]] and [[plucking]] of the underlying [[rock (geology)|rock]]. Abrasion produces fine sediment, termed [[glacial flour]]. The debris transported by the glacier, when the glacier recedes, is termed a [[moraine]]. Glacial erosion is responsible for U-shaped valleys, as opposed to the V-shaped valleys of fluvial origin.
 
=== Weathering ===
 
Main article: [[Weathering]].
 
This results from chemical dissolution of rock and from the mechanical wearing of rock by plant roots, ice expansion, and the abrasive action of sediment. Weathering provides the source of the sediment transported by fluvial, glacial, aeolian, or biotic processes.
 
== Taxonomy ==
 
Different geomorphological processes dominate at different spatial and temporal scales. To help categorize landscape scales some geomorphologists use the following [[taxonomy]]:
* 1st - [[Continent]], [[ocean]] basin, climatic zone (~10,000,000 km²)
* 2nd - Shield, e.g. [[Baltic shield]], or [[mountain range]] (~1,000,000 km²)
* 3rd - Isolated [[sea]], [[Sahel]] (~100,000 km²)
* 4th - Massif, e.g. [[Massif Central]]or Group of related landforms, e.g., [[Weald]] (~10,000 km²)
* 5th - River valley, [[Cotswolds]] (~1,000 km²)
* 6th - Individual [[mountain]] or [[volcano]], small valleys (~100 km²)
* 7th - Hillslopes, stream channels, [[estuary]] (~10 km²)
* 8th - [[gully]], [[barchannel]] (~1 km²)
* 9th - Meter-sized features
Its use, however, is rare and may be misleading - the nature of landscape chage may be better viewed as a continuum of coupled processes.
 
== References ==
 
* [[M. J. Selby]], ''Earth's Changing Surface'' ([[Oxford University Press]], [[1985]]) ISBN 0198232527
* [[Richard Chorley]], [[Stanley Schumm]], and [[David Sugden]], ''Geomorphology'' ([[Methuen]], [[1984]])
 
== See also ==
* [[Base level]]
* [[Biogeology]]
* [[Bioerosion]]
* [[Coastal erosion]]
* [[Denudation]]
* [[Drainage system]]
* [[Erosion]]
* [[Erosion prediction]]
* [[Fluvial landforms of streams]]
* [[Geologic modeling]]
* [[Landslide]]
* [[Lithosphere]]
* [[Meander]]
* [[Peneplain]]
* [[Soil]]
* [[Soil conservation]]
* [[Soil mechanics]]
* [[Soils retrogression and degradation]]
* [[Stream capture]]
* [[Watershed]]
* [[List of publications in geology#Geomorphology| Important publications in geomorphology]]
 
[[Category:Geology]]
[[Category:Physical geography]]
[[Category:Geomorphology]]
[[Category:Archaeological sub-disciplines]]
 
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[[bg:Геоморфология]]
[[ca:Geomorfologia]]
[[cs:Geomorfologie]]
[[cy:Morffoleg (daear)]]
[[de:Geomorphologie]]
[[et:Geomorfoloogia]]
[[es:Geomorfología]]
[[fa:زمین‌ریخت‌شناسی]]
[[fr:Géomorphologie]]
[[hr:Geomorfologija]]
[[nl:Geomorfologie]]
[[pl:Geomorfologia]]
[[zh:地貌学]]