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VectorMap:how to replace a Value [message #29127]

Wed, 06 October 2010 16:17

281264
Messages: 272
Registered: June 2010
Location: Spain

Experienced Member

Hi,

In a VectorMap, is there any way to replace a Value maintaining its Key? Is the only way: Remove the element (by the Key) and to Add it again with the same Key but with the new Value?

Thank you.

Cheers,

Javier

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Re: VectorMap:how to replace a Value [message #29128 is a reply to message #29127]

Wed, 06 October 2010 16:45

cbpporter
Messages: 1428
Registered: September 2007

Ultimate Contributor

Or just simple assignment indexed by key or index?

[Updated on: Wed, 06 October 2010 16:45]

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Re: VectorMap:how to replace a Value [message #29130 is a reply to message #29128]

Wed, 06 October 2010 19:05

281264
Messages: 272
Registered: June 2010
Location: Spain

Experienced Member

Would you mind writing the VectorMap method/function you are mentioning?

Thank you.

Javier

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Re: VectorMap:how to replace a Value [message #29131 is a reply to message #29130]

Wed, 06 October 2010 19:54

dolik.rce
Messages: 1796
Registered: August 2008
Location: Czech Republic

Ultimate Contributor

Hi Javier,

I believe cbporter meant this:

	VectorMap<String,int> map
	map.Get("key")=2;
	map[map.Find("key")]=3;

Sorry for giving you such short answer as well, but those are quite trivial and there is not much to say Smile

Honza

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Re: VectorMap:how to replace a Value [message #29133 is a reply to message #29131]

Wed, 06 October 2010 20:05

281264
Messages: 272
Registered: June 2010
Location: Spain

Experienced Member

Excellent.

Many thanks to you both.

Javier

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Re: VectorMap:how to replace a Value [message #37201 is a reply to message #29131]

Wed, 05 September 2012 09:26

rxantos
Messages: 73
Registered: October 2011

Member

Sorry for the thread necromancy. But both

map.Get("key")=2;
map[map.Find("key")]=3;

Gives an assertion fail when the key is not in the map.

Tried with Add but it will just add another copy instead of replacing the value.

Granted, some times one wants to keep the extra copies. But sometimes is just a waste of memory and cycles.

This, however, seems to work:

int i = map.Find("key");
if(0 > i) {
  map.Add("key",2);
} else {
  map[i] = 2;
}

Maybe a Set Function should be added to AMap

T& Set(const K& k, const T& x) {
  int i = Find(k);
  if(0 > i) {
    return Add(k,x);
  } else {
    value[i] = x;
  }
  return value[i];
}

so that the code becomes:

map.Set("key",2);

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Re: VectorMap:how to replace a Value [message #37203 is a reply to message #37201]

Wed, 05 September 2012 10:02

omari
Messages: 276
Registered: March 2010

Experienced Member

map.GetAdd("key") = 3;

regards
omari.

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Re: VectorMap:how to replace a Value [message #37204 is a reply to message #37201]

Wed, 05 September 2012 10:05

dolik.rce
Messages: 1796
Registered: August 2008
Location: Czech Republic

Ultimate Contributor

Hi rxantos

Such methods already exist Wink

Look at FindAdd and GetAdd in the reference.

Best regards,
Honza

PS: Ahh, omari was faster Smile

[Updated on: Wed, 05 September 2012 10:06]

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