(gawk.info.gz) Truth Values

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 True and False in `awk'
 =======================
 
    Many programming languages have a special representation for the
 concepts of "true" and "false."  Such languages usually use the special
 constants `true' and `false', or perhaps their uppercase equivalents.
 However, `awk' is different.  It borrows a very simple concept of true
 and false from C.  In `awk', any nonzero numeric value _or_ any
 nonempty string value is true.  Any other value (zero or the null
 string `""') is false.  The following program prints `A strange truth
 value' three times:
 
      BEGIN {
         if (3.1415927)
             print "A strange truth value"
         if ("Four Score And Seven Years Ago")
             print "A strange truth value"
         if (j = 57)
             print "A strange truth value"
      }
 
    There is a surprising consequence of the "nonzero or non-null" rule:
 the string constant `"0"' is actually true, because it is non-null.
 (d.c.)
 

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