I have inserted some values in a C++ Map, now I want to edit the value associated with a key. I can insert and delete but how to edit?
Any hints?
I have tried this:
This gives me an error:Code:map <unsigned int, QTcpSocket*> :: iterator objTempIter; objTempIter = mapName.end (); (*objTempIter).first = 22;Code:error: assignment of read-only data-member ‘std::pair<const unsigned int, QTcpSocket*>::first’
Last edited by AnishaKaul; 02-03-2011 at 06:06 AM.
Or something like that.Code:yourMap["keyName"] = newValue;
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Thanks for replying,
Q: Can I edit the key itself?
Q: The value associated with the key is a socket pointer, so even if I exchange the positions of the current key and its value somehow, then how will I write the keyname according to your example in post 2?
Sorry, i don't have any experience with C++'s map class.
What i can tell you is that in the code you've tried it says that "first" can't be changed. That's your problem.
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Just like every other container, .end() is not an actual element of your map, but rather "one past the last valid item".Originally Posted by AnishaKaul
If you want to change the key value, you will have to map the QSocket* to the new int, then remove the previous map element (with something like remove()).
Thanks TabStop, but I didn't understand the following:
map the QSocket* to the new int
Basically, it just means that you add a new element to the map and remove the old one. In this case, adding a new element means that your new integer key will map to the same QTcpSocket pointer as the old integer key.
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I am sorry if I am missing your point again, but did you mean that the previous entry which I want to be edited should be removed and then a fresh entry with the fresh data should be made?
Yes, if you want to change the key.
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Thank you for that, if I have further queries I'll post here again.
