Basic HTML version of Foils prepared March 30 97

Foil 25 Control Structures -- What is true and false (Chapter 4 of the Llama Book)

From PERL4 Tutorial for CPS616 Computational Science for Information Age Course CPS616 -- February 1995. by Geoffrey C. Fox
in PERL all TESTEXPRESSION's are converted to strings and
Either the null string or string '0' (same as "0") is evaluated as FALSE
Everything else evaluates as TRUE
Results of Comparison Operators are what you expect
  • if ( $age < 18 ) evaluates as TRUE iff the numeric value of $age is less than 18
Note the numeric number 0 is converted to "0" and is FALSE as is numeric computation 1-1.
The string "0.000" evaluates as TRUE

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