Substring/Top and tail: Difference between revisions

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m (→‎{{header|REXX}}: redid a boxed comment, added/changed comments and whitespace.)
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===error prone===
===error prone===
This REXX version is error prone in that if the string is less than two characters, then the   '''left'''   and/or   '''substr'''   BIFs will fail   (because of an invalid length specified).
This REXX version is error prone in that if the string is less than two characters, then the   '''left'''   and/or   '''substr'''   BIFs will fail   (because of an invalid length specified).
<lang rexx>/*REXX program demonstrates removal of 1st/last/1st&last chars from a string. */
<lang rexx>/*REXX program demonstrates removal of 1st/last/1st-and-last characters from a string.*/
@ = 'abcdefghijk'
@ = 'abcdefghijk'
say ' the original string =' @
say ' the original string =' @
say 'string first character removed =' substr(@,2)
say 'string first character removed =' substr(@, 2)
say 'string last character removed =' left(@,length(@)-1)
say 'string last character removed =' left(@, length(@) -1)
say 'string first & last character removed =' substr(@,2,length(@)-2)
say 'string first & last character removed =' substr(@, 2, length(@) -2)
/*stick a fork in it, we're all done. */
/*stick a fork in it, we're all done. */
/* ╔═══════════════════════════════════════════════════════════════════════════════╗

║ However, the original string may be null or exactly one byte in length which ║
/* ╔═══════════════════════════════════════════════════════╗
║ However, the original string may be null or exactly ║
║ will cause the BIFs to fail because of either zero or a negative length. ║
╚═══════════════════════════════════════════════════════════════════════════════╝ */</lang>
║ one byte in length which will cause the BIFs to ║
║ fail because of either zero or a negative length. ║
╚═══════════════════════════════════════════════════════╝ */</lang>
'''output'''
'''output'''
<pre>
<pre>
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===robust version===
===robust version===
This REXX version correctly handles a string of zero (null) or one byte.
This REXX version correctly handles a string of zero (null) or one byte.
<lang rexx>/*REXX program demonstrates removal of 1st/last/1st&last chars from a string. */
<lang rexx>/*REXX program demonstrates removal of 1st/last/1st-and-last characters from a string.*/
@ = 'abcdefghijk'
@ = 'abcdefghijk'
say ' the original string =' @
say ' the original string =' @
say 'string first character removed =' substr(@,2)
say 'string first character removed =' substr(@, 2)
say 'string last character removed =' left(@,max(0,length(@)-1))
say 'string last character removed =' left(@, max(0, length(@) -1))
say 'string first & last character removed =' substr(@,2,max(0,length(@)-2))
say 'string first & last character removed =' substr(@, 2, max(0, length(@) -2))
exit /*stick a fork in it, we're all done. */
exit /*stick a fork in it, we're all done. */


/* [↓] an easier to read version using a length variable.*/
/* [↓] an easier to read version using a length variable.*/
@ = 'abcdefghijk'
@ = 'abcdefghijk'
L=length(@)
L=length(@)
say ' the original string =' @
say ' the original string =' @
say 'string first character removed =' substr(@,2)
say 'string first character removed =' substr(@, 2)
say 'string last character removed =' left(@,max(0,L-1))
say 'string last character removed =' left(@, max(0, L-1) )
say 'string first & last character removed =' substr(@,2,max(0,L-2))</lang>
say 'string first & last character removed =' substr(@, 2, max(0, L-2) )</lang>
'''output''' is the same as the 1<sup>st</sup> REXX version.
'''output''' &nbsp; is the same as the 1<sup>st</sup> REXX version.


===faster version===
===faster version===
This REXX version is faster &nbsp; (uses &nbsp; '''parse''' &nbsp; instead of multiple BIFs).
This REXX version is faster &nbsp; (uses &nbsp; '''parse''' &nbsp; instead of multiple BIFs).
<lang rexx>/*REXX program demonstrates removal of 1st/last/1st&last chars from a string. */
<lang rexx>/*REXX program demonstrates removal of 1st/last/1st-and-last characters from a string.*/
@ = 'abcdefghijk'
@ = 'abcdefghijk'
say ' the original string =' @
say ' the original string =' @
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say 'string first character removed =' z
say 'string first character removed =' z


m=length(@)-1
m=length(@) - 1
parse var @ z +(m)
parse var @ z +(m)
say 'string last character removed =' z
say 'string last character removed =' z


n=length(@)-2
n=length(@) - 2
parse var @ 2 z +(n)
parse var @ 2 z +(n)
if n==0 then z= /*handle special case of a length of 2.*/
if n==0 then z= /*handle special case of a length of 2.*/
say 'string first & last character removed =' z
say 'string first & last character removed =' z /*stick a fork in it, we're all done. */</lang>
⚫
'''output''' &nbsp; is the same as the 1<sup>st</sup> REXX version. <br><br>
/*stick a fork in it, we're all done. */</lang>
⚫
'''output''' is the same as the 1<sup>st</sup> REXX version. <br><br>


=={{header|Ring}}==
=={{header|Ring}}==
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