In Solidity, what is the difference between using if() and require()?

Question

I can run code inside a conditional if statement. I can also require a condition before running some code. Are they interchangeable or are there reasons I would choose to rely on one and not the other?

Answer 1

No, they are not interchangeable.

When an if condition is false, the next condition/block is executed and the else block (if any) is run. Standard if/else programming logic.

require is an error handling statement. When a require condition is false, all execution stops and the transaction is rolled back.

See the Solidity documentation for error handling for more info on require and the differences between that and other error handling functions such as assert and revert .