[Development] 答复: [Qt-interest] QMultiHash

pengliang(彭亮) pengliang at founder.com
Thu Mar 7 10:58:43 CET 2013



QmultiHash replace() is only replace first item, I want to replace all values when key is matched.

Qt docs : if there are multiple items with the key, the most recently inserted item's value is replaced with value.

Who have a better method?


2.       so I need to use Qmap<long,Qstring>,

I found qt source code below, so I think Qhash<long,Qstring> is ordered by long, am I right?

inline uint qHash(long key) { return qHash(ulong(key)); }

template <class T> inline uint qHash(const T *key)


    return qHash(reinterpret_cast<quintptr>(key));








发件人: Danny Koppel [mailto:D.Koppel at skf-rif.nl] 
发送时间: 2013年3月7日 17:39
收件人: 'pengliang(??)'; development at qt-project.org
主题: RE: [Development] [Qt-interest] QMultiHash




I don’t know if I understand you correctly but the QMultiHash class has the function replace which does what you describe.

It replaces the value of an existing key or creates a new one if the key doesn’t exist yet.

About point 2: the documentation describes it as follows: “When iterating over a QMap <qthelp://org.qt-project.qtcore.501/qtcore/qmap.html> , the items are always sorted by key. With QHash, the items are arbitrarily ordered.”.


Kind regards,



Van: development-bounces+d.koppel=skf-rif.nl at qt-project.org [mailto:development-bounces+d.koppel=skf-rif.nl at qt-project.org] Namens pengliang(??)
Verzonden: donderdag 7 maart 2013 10:25
Aan: development at qt-project.org
Onderwerp: [Development] [Qt-interest] QMultiHash


Hi All



I need to find some key and change their values.

I found If I use QmutableHashIterator<Qstring,int>it , its 


findNext ( const T & value )

Its parameter is a value, not a key.

So I need to :




If(it.key() == ikey)





I must to check every item? Who have a better method?


2. Qhash:

Some books said Qhash is unorderred?

But I test it.


I insert some string, and loop the hash by QhashIterator, I found the string is orderred.

And I test it Qhash<int,Qstring>, and print key, and found they still orderred.

Why books said it is unorderred?






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