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--- jvs:fscan:manual:chapter1:stringsubst [2018/12/12 19:39]
voyvodic
+++ jvs:fscan:manual:chapter1:stringsubst [2023/02/23 18:43] (current)
@@ Line 19: / Line 19: @@
   set myage 42
-Variable names are identified by an initial '$' or '_' character. Either prefix can be used for any variable; the variable is replaced by its string value in both cases. For single-valued variables '$' and '_' behave identically. But if the variable contains multiple words (separated by spaces) then a single '$' variable argument in a command will be converted to multiple single-word arguments, whereas a '_' multi-word variable argument remains a single argument.
+Variable names are identified by an initial '$' or '_' character. Either prefix can be used for any variable; the variable is replaced by its string value in both cases. The '_' identifier is recommended if you are specifying a string variable on a fScan command line because the '$' character means something different to shell command interpreters. Otherwise the '$' and '_' identifiers behave identically for single-valued variables. But if the variable contains multiple words (separated by spaces) then a single '$' variable argument in a command will be converted to multiple single-word arguments, whereas a '_' multi-word variable argument remains a single argument.
 To perform simple arithmetic simply follow a variable name with '+', '-', '*', or '/' and a number value (no spaces). For example
    set newage $myage+3
-   echo Image center is $xdim/2 $ydim/2 $zdim/2
+   echo "Image center location is:" $xdim/2 $ydim/2 $zdim/2

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