CODEWITHSUNDEEP
c++qtqbytearray
code_fodder
code_fodder

Reputation: 16341

QByteArray get the address of nth element

I have the following code that I need to translate into qt from plain c++:

// txMessage and UserData are char arrays
memcpy(&txMessage[18], UserData, 8);

So my conversion is like this:

QByteArray txMessage;
txMessage.resize(26);
    :
    :
memcpy(&(txMessage.data()[18]), UserData, 8);

So this should work, but looks messy. I have to get the data pointer using the data() function and then reference element 18 with [18] and then take the address of that with &.

I looked through the whole QByteArray docs online and can't see another function that returns char* and operator [] only returns a temp variable, so can't address that. But there are so many options/functions for QByteArray maybe I missed something? Anyone found/got a better way to get the address of nth element in QByteArray?

EDIT There are a few things that appear to be undocumented in QByteArray:

Upvotes: 0

Views: 1328

Answers (1)

Holt
Holt

Reputation: 37616

You should use the replace method instead:

txMessage.replace(18, 8, UserData, 8) ;

If you are using a Qt version less than 4.7, but your UserData variable is null-terminated, then simply:

txMessage.replace(18, 8, UserData) ;

Otherwize:

memcpy(txMessage.data() + 18, UserData, 8);

Upvotes: 2

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