Using push_back of vector to report error in lambda expression

[monkey233]

    std::vector<int> ii;
     connect(but1, &QPushButton::clicked, this, [&]() {
	ii.push_back(1);
});

breakdown when i push the button. qvector is the same.

[J.Hilk]

@monkey233 more information please, is ii local scope or a class member ?

[monkey233]

@monkey233 said in Using push_back of vector to report error in lambda expression:

Thank you for your reply. I'm a novice.sorry I don't know what you mean.i think ii is vector<int>. These three sentences together are correct when compiling. I omitted the statement of creating button.

[JonB]

@monkey233
So if it's exactly as you show, ii is a local variable to the method you are in. That means it goes out of scope (i.e. gets destroyed) when you exit that function. Meanwhile, you have a lambda-slot attached to the signal which still references that variable, which now does not exist. Kaputt....

Presumably, if you want that to do anything permanent/meaningful, std::vector<int> ii needs to be a member variable in your class, so that it persists.

[monkey233]

thank you,i will try