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crpl:docs:eq [2013/12/03 17:38] – Added not on comparing unlike types Grauniadcrpl:docs:eq [2025/02/14 14:57] (current) – external edit 127.0.0.1
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-~~DISCUSSION~~+
 <- [[crpl:crplreference| CRPL reference]] <- [[crpl:crplreference#comparators|Comparators]] <- [[crpl:crplreference| CRPL reference]] <- [[crpl:crplreference#comparators|Comparators]]
 =====  eq  ===== =====  eq  =====
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 === Comparing unlike types === === Comparing unlike types ===
 When trying to do a comparison where one argument is a string and the other is an int, the string gets coerced into an int.  If the string is something like "42" that coerces into 42.  If it is "abc" that coerces into 0. When trying to do a comparison where one argument is a string and the other is an int, the string gets coerced into an int.  If the string is something like "42" that coerces into 42.  If it is "abc" that coerces into 0.
 +
 +In particular, if x may be a string or number, (<-x "abc" eq) will unexpectedly return true when x equals 0. One remedy is to coerce x to a string before comparing as in (<-x "" concat "abc" eq).
  
 The 'eq' (and other comparators) look at both arguments and their intrinsic types.  The rules are: The 'eq' (and other comparators) look at both arguments and their intrinsic types.  The rules are:
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 45 50 gt        # False, 45 is not greater than 50  45 50 gt        # False, 45 is not greater than 50 
 50 50 gt        # False, 50 is not greater than 50</code>  50 50 gt        # False, 50 is not greater than 50</code> 
 +
 +Examples of comparing with unlike types
 +<code>
 +"string" ->string
 +0 ->zero
 +1 ->one
 +Trace(<-string eq(<-one)) # returns 0/FALSE
 +Trace(<-string eq(<-zero)) # returns 1/TRUE
 +
 +"1" ->OneAsString
 +Trace(<-OneAsString eq(<-one)) # returns 1/TRUE
 +Trace(<-OneAsString eq(<-zero)) # returns 0/FALSE
 +</code>
 +
 +<code>
 +# If core doesn't have Script.crpl attached, GetScriptVar will return 0.
 +# Then "MyScript" is coerced to 0 and the result is TRUE.
 +Trace(GetScriptVar(<-core "Script.crpl" "name") "MyScript" eq)
 +# The following version returns TRUE only if core has Script.crpl attached with
 +# a variable "name" whose value is the string "MyScript".
 +Trace(GetScriptVar(<-core "Script.crpl" "name") "" concat "MyScript" eq)
 +</code>
  
crpl/docs/eq.1386092300.txt.gz · Last modified: 2025/02/14 14:56 (external edit)

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