Here's another stab at a possible solution. A robust parser such as has been discussed by others would probably be better, but something like this may serve. 

c:\@Work\Perl>perl -wMstrict -le
"my $operators = '+-*/';
 my %disp =
   map { $_ => eval qq{ sub { return \$_[0] $_ \$_[1] } } }
   split '', $operators
   ;
 my $int = qr{ [-+]? \d+        }xms;
 my $op  = qr{ [\Q$operators\E] }xms;
 ;;
 my $t = 'foo 1  + 2 bar 34*56 baz 3-  4 and 56  /78 too';
 ;;
 for my $s ($t, @ARGV) {
   print '';
   print qq{'$s'};
   $s =~ s{ ($int) \s* ($op) \s* ($int) }{ $disp{$2}->($1, $3) }xmsge;
   print qq{'$s'};
   }
"  "x-3--4,-3++4"  "foo+bar"

'foo 1  + 2 bar 34*56 baz 3-  4 and 56  /78 too'
'foo 3 bar 1904 baz -1 and 0.717948717948718 too'

'x-3--4,-3++4'
'x1,1'

'foo+bar'
'foo+bar'

[download]
... code to make you understand my problem ...

In this spirit, I was tempted to post only the code from the statement
    my $t = 'foo 1  + 2 bar 34*56 baz 3-  4 and 56  /78 too';
on down and title it something like "code to make you understand my solution", but let's just say no more...

Update: For instance, the code above fails for something as simple as  "1 + 2 + 3" which even a fairly simple parser could handle. But again, we don't know just what's really needed...

In reply to Re: converting from str to int by AnomalousMonk
in thread converting from str to int by Anonymous Monk

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