public member function
<map>
void clear();
void clear() noexcept;
Clear content
0.
Removes all elements from the map container (which are destroyed), leaving the container with a size of
Tóm Tắt
Parameters
none
Return value
none
Example
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// map::clear
#include <iostream>
#include <map>
int main ()
{
std::map<char,int> mymap;
mymap['x']=100;
mymap['y']=200;
mymap['z']=300;
std::cout << "mymap contains:\n";
for (std::map<char,int>::iterator it=mymap.begin(); it!=mymap.end(); ++it)
std::cout << it->first << " => " << it->second << '\n';
mymap.clear();
mymap['a']=1101;
mymap['b']=2202;
std::cout << "mymap contains:\n";
for (std::map<char,int>::iterator it=mymap.begin(); it!=mymap.end(); ++it)
std::cout << it->first << " => " << it->second << '\n';
return 0;
}
Output:
mymap contains: x => 100 y => 200 z => 300 mymap contains: a => 1101 b => 2202
Output:
Complexity
Linear in
Linear in size (destructions).
Iterator validity
All iterators, pointers and references related to this container are invalidated.
Data races
The container is modified.
All contained elements are modified.
Exception safety
No-throw guarantee: this member function never throws exceptions.