Another update from ingydotnet^djgoku

Task/Substring-Top-and-tail/REXX/substring-top-and-tail-1.rexx

@@ -0,0 +1,13 @@
+/*REXX program demonstrates removal of 1st/last/1st&last chars from a string. */
+@ = 'abcdefghijk'
+say '                  the original string ='  @
+say 'string first        character removed ='  substr(@,2)
+say 'string         last character removed ='  left(@,length(@)-1)
+say 'string first & last character removed ='  substr(@,2,length(@)-2)
+                                       /*stick a fork in it,  we're all done. */
+
+                 /* ╔═══════════════════════════════════════════════════════╗
+                    ║  However, the original string may be null or exactly  ║
+                    ║  one byte in length   which  will cause the  BIFs to  ║
+                    ║  fail because of  either zero  or  a negative length. ║
+                    ╚═══════════════════════════════════════════════════════╝ */

Task/Substring-Top-and-tail/REXX/substring-top-and-tail-2.rexx

@@ -0,0 +1,15 @@
+/*REXX program demonstrates removal of 1st/last/1st&last chars from a string. */
+@ = 'abcdefghijk'
+say '                  the original string ='  @
+say 'string first        character removed ='  substr(@,2)
+say 'string         last character removed ='  left(@,max(0,length(@)-1))
+say 'string first & last character removed ='  substr(@,2,max(0,length(@)-2))
+exit                                   /*stick a fork in it,  we're all done. */
+
+                    /* [↓]  an easier to read version using a length variable.*/
+@ = 'abcdefghijk'
+L=length(@)
+say '                  the original string ='  @
+say 'string first        character removed ='  substr(@,2)
+say 'string         last character removed ='  left(@,max(0,L-1))
+say 'string first & last character removed ='  substr(@,2,max(0,L-2))

Task/Substring-Top-and-tail/REXX/substring-top-and-tail-3.rexx

@@ -0,0 +1,16 @@
+/*REXX program demonstrates removal of 1st/last/1st&last chars from a string. */
+@ = 'abcdefghijk'
+say '                  the original string =' @
+
+parse var @ 2 z
+say 'string first        character removed =' z
+
+m=length(@)-1
+parse var @ z +(m)
+say 'string         last character removed =' z
+
+n=length(@)-2
+parse var @ 2 z +(n)
+if n==0  then z=                       /*handle special case of a length of 2.*/
+say 'string first & last character removed =' z
+                                       /*stick a fork in it,  we're all done. */

Task/Substring-Top-and-tail/REXX/substring-top-and-tail.rexx

@@ -1,19 +0,0 @@
-/*REXX program to show removal of 1st/last/1st&last chars from a string.*/
-z = 'abcdefghijk'
-
-say '                  the original string =' z
-say 'string first        character removed =' substr(z,2)
-say 'string         last character removed =' left(z,length(z)-1)
-say 'string first & last character removed =' substr(z,2,length(z)-2)
-exit
-        /* ┌───────────────────────────────────────────────┐
-           │ however, the original string may be null,     │
-           │ or of insufficient length which may cause the │
-           │ BIFs to fail  (because of negative length).   │
-           └───────────────────────────────────────────────┘ */
-
-say '                  the original string =' z
-say 'string first        character removed =' substr(z,2)
-say 'string         last character removed =' left(z,max(0,length(z)-1))
-say 'string first & last character removed =' substr(z,2,max(0,length(z)-2))
-                            /*stick a fork in it,we're done.*/