>>20
I am not flaming. That said, I think it is worth it to study how to make a very simple GUI instead. Need input? Use a javascript-like dialog "Please enter the amount in dollars --> " with the textfield next to it.
It's simple. When you need output, just accumulate stuff to a buffer and put that buffer in a textfield with scrollers. It infinitely beats console data because that tends to be discarded when you large output. Plus scrollers are awesome, and consoles have poor ways of interacting when you actually want to copy and paste somewhere.
Use console if you are a unix person who will pipe the data somewhere else for further processing.
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That said, to answer the thread question, the one thing I think everyone should know is the Java-pushed properVariableNameCreation that beats the __Hell_out_OFcPlus-plus variables and namespace chaos from using libraries.