send_message.sol

pragma solidity >=0.7.0 <0.9.0;

contract Chat {
  
  // ...
  
  // We can use an autoincremental id for each new message.
  uint lastMessageId;
  
  function sendMessage(string _text) public {
    // increments id and sends message.
    lastMessageId++;
    sendMessageEvent(lastMessageId, msg.sender, _text);
  }
}

I don't understand one thing:
When sendMessage() function is called then the lastMessageId is incremented which I suppose it's used by sendMessageEvent event. But instead a different value (messageIdCounter) is used.

BTW - I got this code from the Blockchain chat server application written in Solidity article. Thanks for sharing!

Hi Nicolas! Yes, you are totally right, I refactored the variable name and I forgot to replace it in that line. Anyway, the full function code seems to be right. Thanks a lot for the correction :)