leading zeros in for/foreach loops

leading zeros in for/foreach loops

[Andy Spiegl]

% for i in {01..03}; echo $i
01
02
03

% foreach i ( {01..03} ); echo $i; end
01
02
03

But these two commands don't give me leading zeros if I FIRST run this:
% for ((i=1;i<=3;i++)) echo $i
1
2
3

Can someone please explain this to me?  Does this for loop do
something strange with the variable "i"?  How can I avoid that?

Thanks so much!
 Andy


-- 
 Our scientific power has outrun our spiritual power.
 We have guided missiles and misguided men.
   (Martin Luther King Jr.)

Re: leading zeros in for/foreach loops

[Bart Schaefer]

On Feb 15,  7:07pm, Andy Spiegl wrote:
}
} Can someone please explain this to me?  Does this for loop do
} something strange with the variable "i"?  How can I avoid that?

If the first assignment to an undeclared variable occurs in an
arithmetic context, the variable is given numeric type (integer or
float, depending on what has been assigned to it).  "for (( ... ))"
syntax is such a context.

You can avoid this implicit declaration by explicitly declaring the
variable before using it in any of your loops, e.g., "typeset i" or
"declare i" or "local i" or the appropriate synonym.  Or "unset i"
after the loop is finished.