C++ STL map::erase a non-existing key

Question

Regarding the C++ STL map, erasing by key:-

 size_type map::erase ( const key_type& x );

Is it legal to erase a non-existing key? i.e. is the snippet below ok?

map<char,int> mymap;
mymap['c']=30;
mymap.erase('c');
mymap.erase('c');
mymap.erase('D');

Cheers

score 90 · Accepted Answer · edited Aug 28 '13 at 07:29

90

Yes, in fact, std::map::erase() returns a size_type which indicates the number of keys erased. Thus it returns 0 for nothing erased and 1 for something erased for a map.

edited Aug 28 '13 at 07:29

answered Mar 30 '09 at 01:22

rlbond

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score 13 · Answer 2 · answered Mar 30 '09 at 01:23

13

This is perfectly fine, mymap.erase('D') will return 0 in this case.

See http://www.cplusplus.com/reference/stl/map/erase.html

answered Mar 30 '09 at 01:23

brian-brazil

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C++ STL map::erase a non-existing key

2 Answers2