<![CDATA[Why VerticalHeaderItem cause crit.error]]>When i add any action to my VertHItem - in runtime it cause crit error and the program stop working. I've included QHeaderView, certain Item indeed exist, but i simply can't set text for it:

if(tabWidGuide.verticalHeaderItem(0)->text()=="1") tabWidGuide.verticalHeaderItem(0)->setBackground(Qt::red);

That code assures that item at '0' exist and it's label is 1, which is true, it 1 by default in my app.

P.S. here is it in documentation

]]>https://forum.qt.io/topic/96370/why-verticalheaderitem-cause-crit-errorRSS for NodeTue, 14 Jul 2026 13:19:31 GMTTue, 06 Nov 2018 21:27:24 GMT60<![CDATA[Reply to Why VerticalHeaderItem cause crit.error on Wed, 07 Nov 2018 20:41:48 GMT]]>@Engelard said in Why VerticalHeaderItem cause crit.error:

i assume that it set by default,

It isn't.

]]>https://forum.qt.io/post/491818https://forum.qt.io/post/491818Wed, 07 Nov 2018 20:41:48 GMT<![CDATA[Reply to Why VerticalHeaderItem cause crit.error on Wed, 07 Nov 2018 20:38:25 GMT]]>@aha_1980 i didn't set anything, i assume that it set by default, so why would i set it..

]]>https://forum.qt.io/post/491816https://forum.qt.io/post/491816Wed, 07 Nov 2018 20:38:25 GMT<![CDATA[Reply to Why VerticalHeaderItem cause crit.error on Wed, 07 Nov 2018 17:58:15 GMT]]>@Engelard

Why it exist in the app, and it returning like it does'nt?

  • How do you set it?
  • Do you set it before your read it back?
]]>https://forum.qt.io/post/491794https://forum.qt.io/post/491794Wed, 07 Nov 2018 17:58:15 GMT<![CDATA[Reply to Why VerticalHeaderItem cause crit.error on Wed, 07 Nov 2018 15:04:36 GMT]]>Tnx for all advices for checking item, now it shows that header does'nt exist. BUT. Why it exist in the app, and it returning like it does'nt?

]]>https://forum.qt.io/post/491780https://forum.qt.io/post/491780Wed, 07 Nov 2018 15:04:36 GMT<![CDATA[Reply to Why VerticalHeaderItem cause crit.error on Wed, 07 Nov 2018 09:35:17 GMT]]>@jsulm , @aha_1980
I agree with your advice. However, I took the OP at his word when his question states

[I am] certain Item indeed exist

I shall be interested to see whether he comes back and says that pointer was NULL after all, maybe I'm too trusting...!

]]>https://forum.qt.io/post/491730https://forum.qt.io/post/491730Wed, 07 Nov 2018 09:35:17 GMT<![CDATA[Reply to Why VerticalHeaderItem cause crit.error on Wed, 07 Nov 2018 07:15:08 GMT]]>@Engelard

And that's exactly the difference between pointers and references you have to understand.

Pointers have to be checked against nullptr before de-referencing, references can always be used.

]]>https://forum.qt.io/post/491698https://forum.qt.io/post/491698Wed, 07 Nov 2018 07:15:08 GMT<![CDATA[Reply to Why VerticalHeaderItem cause crit.error on Wed, 07 Nov 2018 06:05:58 GMT]]>@Engelard said in Why VerticalHeaderItem cause crit.error:

if(tabWidGuide.verticalHeaderItem(0)->text()=="1") tabWidGuide.verticalHeaderItem(0)->setBackground(Qt::red);

To add to @mrjj : you should ALWAYS check pointers before dereferencing them!

if(tabWidGuide.verticalHeaderItem(0) && tabWidGuide.verticalHeaderItem(0)->text()=="1") tabWidGuide.verticalHeaderItem(0)->setBackground(Qt::red);
]]>https://forum.qt.io/post/491689https://forum.qt.io/post/491689Wed, 07 Nov 2018 06:05:58 GMT<![CDATA[Reply to Why VerticalHeaderItem cause crit.error on Tue, 06 Nov 2018 21:29:38 GMT]]>Hi
You should check its not NULL
try
qDebug() << "item = " << tabWidGuide.verticalHeaderItem(0);

]]>https://forum.qt.io/post/491646https://forum.qt.io/post/491646Tue, 06 Nov 2018 21:29:38 GMT