Code With No Effects

In Solidity, it's possible to write code that does not produce the intended effects.

Let's see an example:

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The line

    balance[msg.sender] == amount;

has an error which is very unpleasant. Instead the right way is to assign the amount to the balance of the msg.sender, like this:

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Another bad example is this code snippet:

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As you can see, here we are not checking the return value of the call on this line:

    msg.sender.call.value(amount);

And the fix is the following:

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