How do I see how much ether was sent to a contract when it was called?

Question

I want to implement a contract where users are required to deposit a certain amount of money in order to participate. If the user doesn't send enough money, I simply want to send it back to them and not include them in the protocol. How do I see how many eth msg.sender sent to the contract when they called it? Is this even possible?

Answer 1

Use msg.value.

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