How does QString::qHash() work?

**Morea** · 7th September 2009, 08:04

How does Qt calculate a hash value for a string?

Does anyone here know that?

**nish** · 7th September 2009, 08:19

are we talking about QCryptographicHash ?
coz qHash is used for a different purpose i think.

**Morea** · 7th September 2009, 08:31

I'm talking about the hashvalue that is calculated for a QString when inserted into a QHash<QString, some_type>

**nish** · 7th September 2009, 08:36

well. then you can just take a look at the qt sources for qHash function..

**wysota** · 7th September 2009, 09:17

Originally Posted by Morea

How does Qt calculate a hash value for a string?

Originally Posted by MrDeath

are we talking about QCryptographicHash ?

The principle is exactly the same, except that cryptographic hash should have a larger number of possible results (value space).

An easy (although completely useless) qHash implementation would be to sum the ascii values of all characters in the string and return that as a value (normalized to the value space).