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

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.

See also