Variable inside lambda function is showing garbage value - c++

Question

I am using this method in a Cocos2d X game.
void OpponentNode::discard(int cardNum)
{
log("\nOpponentNode::discard <%d>\n", cardNum);
for (int i = 0; i < vecOpponentHand.size(); i++)
{
if (vecOpponentHand.at(i) == cardNum)
{
vecOpponentHand.erase(vecOpponentHand.begin() + i);
break;
}
}
CardSprite * discardedCard;
for (int i = 0; i < vecOpponentCards.size(); i++)
{
if (vecOpponentCards.at(i)->getTag() == cardNum)
{
discardedCard = vecOpponentCards.at(i);
vecOpponentCards.erase(vecOpponentCards.begin() + i);
break;
}
}
log("\nOpponentNode::discard <%d>\n", cardNum);
discardedCard->makeFaceUp();
RotateTo * rotate = RotateTo::create(0.4 * SPEED_MULTIPLIER, 0);
MoveTo * move = MoveTo::create(0.4 * SPEED_MULTIPLIER,
origin + Vec2(visibleSize.width * 0.75, visibleSize.height * 0.6));
Spawn * spawn = Spawn::create(rotate, move, NULL);
CallFunc * callFunc = CallFunc::create(
[&]()
{
log("\nOpponentNode::discard <%d>\n", cardNum); //this one shows garbage/different value
if (delegate)
{
delegate->opponentNodeDidFinishDiscard(this, cardNum);
}
this->removeChild(discardedCard);
});
discardedCard->runAction(Sequence::create(spawn, callFunc, NULL));
log("\nOpponentNode::discard <%d>\n", cardNum);
}
Strangely, when I log the integer cardNum like above, I get different value from the log inside the lambda function. For example, I get "OpponentNode::discard <402>" from the top 2 logs and the bottom most log but get "OpponentNode::discard <64>" from the log inside the lambda function.
Other points:
The lambda block is executed last.
I mostly get values like 64 or garbage values like -15493456.
My guess is the integer cardNum is getting deallocated before the execution. Can anyone point me to the right direction?

Answer 1

You're capturing a reference to the cardNum parameter. I would think you want to capture that one by value.
It's not clear to me what delegate is. Assuming it's a class member then I think you just need [this, discardedCard, cardNum]. Which you could abbreviate to just [=], although I think the explicit one is clearer.