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Update to my latest expr (fixes bugs with comparison and matching operators)
Add man page I wrote.
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J.T. Conklin
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=181
131
bin/expr/expr.1
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131
bin/expr/expr.1
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.\" Copyright (c) 1993 Winning Strategies, Inc.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by Winning Strategies, Inc.
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.\" 4. The name of the author may not be used to endorse or promote products
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.\" derived from this software withough specific prior written permission
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $Header: /b/source/CVS/src/bin/expr/expr.1,v 1.1 1993/07/20 20:16:26 jtc Exp $
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.\"
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.Dd July 3, 1993
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.Dt EXPR 1
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.Os
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.Sh NAME
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.Nm expr
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.Nd evaluate expression
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.Sh SYNOPSIS
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.Nm expr
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.Ar expression
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.Sh DESCRIPTION
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The
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.Nm expr
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utility evaluates
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.Ar expression
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and writes the result on standard output.
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.Pp
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All operators are separate arguments to the
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.Nm expr
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utility.
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Characters special to the command interpreter must be escaped.
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.Pp
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Operators are listed below in order of increasing precidence.
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Operators with equal precidence are grouped within { } symbols.
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.Bl -tag -width indent
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.It Ar expr1 Li | Ar expr2
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Returns the evaluation of
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.Ar expr1
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if it is neither an empty string nor zero;
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otherwise, returns the evaluation of
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.Ar expr2 .
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.It Ar expr1 Li & Ar expr2
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Returns the evaluation of
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.Ar expr1
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if neither expression evaluates to an empty string or zero;
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otherwise, returns zero.
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.It Ar expr1 Li "{=, >, >=, <, <=, !=}" Ar expr2
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Returns the results of integer comparision if both arguments are integers;
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otherwise, returns the results of lexical comparison.
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The result of each comparison is 1 if the specified relation is true,
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or 0 if the relation is false.
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.It Ar expr1 Li "{+, -}" Ar expr2
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Returns the results of addition or subtraction of integer-valued arguments.
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.It Ar expr1 Li "{*, /, %}" Ar expr2
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Returns the results of multiplication, integer division, or remainder of integer-valued arguments.
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.It Ar expr1 Li : Ar expr2
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The
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.Dq \:
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operator matches
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.Ar expr1
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against
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.Ar expr2 ,
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which must be a regular expression. The regular expression is anchored
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to the begining of the string with an invisible
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.Dq ^ ,
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therefore
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.Dq ^
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is not a special character.
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.Pp
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If the pattern contains at lest one regular expression
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subexpression
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.Dq "\e(...\e)" ,
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the string corresponding to
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.Dq "\e1"
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is returned;
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otherwise the matching operator returns the number of characters matched.
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.El
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.Pp
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Parentheses are used for grouping in the usual manner.
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.Sh EXAMPLES
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.Bl -enum
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.It
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The following example adds one to the variable a.
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.Dl a=`expr $a + 1`
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.It
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The following example returns the filename portion of a pathname stored
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in variable a. The // characters act to eliminate ambiguity with the
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division operator.
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.Dl expr "//$a" Li : '.*/\e(.*\e)'
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.It
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The following example returns the number of characters in variable a.
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.Dl expr $a Li : '.*'
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.El
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.Sh DIAGNOSTICS
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The
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.Nm expr
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utility exits with one of the following values:
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.Bl -tag -width Ds
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.It 0
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the expression is neither an empty string nor 0.
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.It 1
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the expression is an empty string or 0.
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.It 2
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the expression is invalid.
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.El
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.Sh STANDARDS
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The
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.Nm expr
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utility
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is expected to be
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.St -p1003.2
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compatible.
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@ -2,7 +2,7 @@
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/* Written by Pace Willisson (pace@blitz.com)
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* and placed in the public domain
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*
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* /b/source/CVS/src/bin/expr/expr.y,v 1.6 1993/06/14 19:59:07 jtc Exp
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* $Header: /b/source/CVS/src/bin/expr/expr.y,v 1.9 1993/07/20 01:10:55 jtc Exp $
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*/
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#include <stdio.h>
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#include <stdlib.h>
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@ -219,13 +219,10 @@ int
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is_zero_or_null (vp)
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struct val *vp;
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{
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/* Like most other versions of expr, this version will return
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false for a string value of multiple zeros.*/
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if (vp->type == integer) {
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return (vp->u.i == 0);
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} else {
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return (*vp->u.s == 0 || strcmp (vp->u.s, "0") == 0);
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return (*vp->u.s == 0 || (to_integer (vp) && vp->u.i == 0));
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}
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/* NOTREACHED */
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}
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@ -292,12 +289,6 @@ struct val *a, *b;
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{
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struct val *r;
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/* attempt to coerce both arguments to integers */
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(void) to_integer (a);
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(void) to_integer (b);
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/* But if either one of them really is a string, do
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a string comparison */
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if (isstring (a) || isstring (b)) {
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to_string (a);
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to_string (b);
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@ -317,12 +308,6 @@ struct val *a, *b;
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{
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struct val *r;
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/* attempt to coerce both arguments to integers */
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(void) to_integer (a);
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(void) to_integer (b);
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/* But if either one of them really is a string, do
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a string comparison */
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if (isstring (a) || isstring (b)) {
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to_string (a);
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to_string (b);
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@ -342,12 +327,6 @@ struct val *a, *b;
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{
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struct val *r;
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/* attempt to coerce both arguments to integers */
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(void) to_integer (a);
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(void) to_integer (b);
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/* But if either one of them really is a string, do
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a string comparison */
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if (isstring (a) || isstring (b)) {
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to_string (a);
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to_string (b);
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@ -367,12 +346,6 @@ struct val *a, *b;
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{
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struct val *r;
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/* attempt to coerce both arguments to integers */
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(void) to_integer (a);
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(void) to_integer (b);
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/* But if either one of them really is a string, do
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a string comparison */
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if (isstring (a) || isstring (b)) {
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to_string (a);
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to_string (b);
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@ -392,12 +365,6 @@ struct val *a, *b;
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{
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struct val *r;
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/* attempt to coerce both arguments to integers */
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(void) to_integer (a);
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(void) to_integer (b);
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/* But if either one of them really is a string, do
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a string comparison */
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if (isstring (a) || isstring (b)) {
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to_string (a);
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to_string (b);
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@ -417,12 +384,6 @@ struct val *a, *b;
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{
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struct val *r;
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/* attempt to coerce both arguments to integers */
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(void) to_integer (a);
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(void) to_integer (b);
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/* But if either one of them really is a string, do
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a string comparison */
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if (isstring (a) || isstring (b)) {
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to_string (a);
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to_string (b);
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@ -542,8 +503,12 @@ struct val *a, *b;
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regmatch_t rm[SE_MAX];
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char errbuf[256];
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int eval;
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char *newpat;
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struct val *v;
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char *newpat;
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/* coerce to both arguments to strings */
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to_string(a);
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to_string(b);
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/* patterns are anchored to the beginning of the line */
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newpat = malloc (strlen (b->u.s) + 2);
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