learn_gnuawk

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The exercises reads:

The input file nums.txt contains a single column of numbers. Change positive numbers to negative and vice versa. Solution should use the sub function and shouldn't explicitly use the if-else control structure or the ternary operator.

The reference solution indeed relies on sub:

awk '!sub(/^-/, ""){sub(/^/, "-")} 1' nums.txt

But the most elegant solution would be simply:

awk '{ print -$0 }' nums.txt

In fact, the elegant solution would work correctly in case the input file contained a zero value (0), whereas the reference solution would substitute 0 with -0.

Perhaps the conditions of the exercise need to be defined differently if the point is to really rely on sub and its return value.

Hmm, yeah. The main intention was to force the use of sub function and its return value. I'll probably try to come up with a different string manipulation data instead of relying on numbers that could be solved in a simpler way.

Thanks!