J3/04-224

Date:      2004-01-29
To:        J3
From:      fortran.com
Subject:   Single character substring selection
Reference: Pub-114


This was submitted by James Giles  jamesgiles@att.net

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Number:

Title: Single character substring selection

Submitted by: J3

Status: For Consideration

References: FCD, Section 6

Basic Functionality: Eliminate the need for the colon when you want a
substring consisting of a single character.

Rationale: When an expression describing which character you want to
extract is complex, the necessity to repeat it on both
sides of the colon is verbose, error prone, and redundant.

Two examples from note 6.3 using the recommended new form:

   P%name(1)   ! first character on name
   '0123456789'(N+1)   ! the digit corresponding to N

Estimated Impact: Little impact.  No existing conforming code need be
changed.  Implementations will have to support a slightly
different subscripting.  But, since it will be more
consistent with how arrays are subscripted, it won't be
mush of a change (may even make implementation easier).

Detailed Specification: Change R611 to read:

   R611  substring-range is [scalar-int-expr] [: [scalar-int-expr]]

After line 104:17 add:

   If only the first scalar-int-expr is present and no colon
   is used, the length of the substring is one.


History: Submitted as Pub-114