25 lines
650 B
Text
25 lines
650 B
Text
$Prompt {
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`\nEnter two numbers between -1000 and +1000,\nseparated by a space: ' print flush
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} def
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$GetNumbers {
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mark stdin readline pop # Reads input as a string. Pop gets rid of false.
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cvx eval # Convert string to integers.
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} def
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$CheckRange { # (n1 n2 -- bool)
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dup -1000 ge exch 1000 le and
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} def
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$CheckInput {
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counttomark 2 ne
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{`You have to enter exactly two numbers.\n' print flush quit} if
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2 ndup CheckRange exch CheckRange and not
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{`The numbers have to be between -1000 and +1000.\n' print flush quit} if
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} def
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$Answer {
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add cvs `The sum is ' exch cat `.\n' cat print flush
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} def
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Prompt GetNumbers CheckInput Answer
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