Is it possible to return something when the condition inside the require fails?

Question

Is it possible to return 0 inside a function in contract when the condition inside the require results to false?

contract MyContract {
     function initialize() public payable returns (uint) {
        require(10 ** 15 < msg.value); //return 0 if this fails
        return 1; //otherwise return 1
}

Answer 1

Well, you can try to use try-catch

Currently, Solidity supports different kinds of catch blocks depending on the type of error. If the error was caused by revert("reasonString") or require(false, "reasonString") (or an internal error that causes such an exception), then the catch clause of the type catch Error(string memory reason) will be executed.

Inside the catch block return the value you desire like in this example:

try initialize() returns (uint v) {
        return true;
    } catch Error(string memory /*reason*/) {
        // This is executed in case
        // revert was called inside initialize
        // and a reason string was provided.
        
        return false;
}

Because initialize is payable, you need to call it in the correct way with funds

Answer 2

No, if the require function is evaluated to false, nothing is returned because the code has stopped executing.

See: https://docs.soliditylang.org/en/v0.8.16/control-structures.html

Answer 3

Yes

function throwErr() public {
require(err == true, "0");
}

if false, 0 will be displayed as the error message.

Answer 4

If you are calling an external function, you can use the try/catch structure to catch the error and return/log something different, like false indicating that there was a problem and probably also emitting an event. Because if you make changes to the state, emitting events, etc., and then an exception happens, all that will be reverted.