【Solidity】How to output the debug log?

This section explains how to output the debug log in Solidity.

It is assumed that you are using Remix (Ethereum IDE).

Syntax

This section describes how to output and check the debug log.

How to output

To output the debug log in Solidity, do the following

The description of event/emit is a set.

You can also set multiple arguments to an event.

event event name(argument 1[data type], argument 2[data type], ..., argument n[data type]);
emit event name(value 1, value 2, ..., value N);

How to confirmation

To view the debug log in Solidity, expand the arrow icon to the right of the "Debug" button.

Then, check the values of "event" and "args" by looking at the "logs" entry in the debug contents.

Sample Code

// SPDX-License-Identifier: GPL-3.0

pragma solidity >=0.7.0 <0.9.0;

contract Test {

    event DebugLogEvent(string); // single argument
    event DebugLogEventByUser(address, string); // multiple argument
    
    string message = "Hello World";

    function printDebugLog() public {
        emit DebugLogEvent(message);
    }

    function printDebugLogByUser() public {
        emit DebugLogEventByUser(msg.sender, message);
    }

}