Re: delete columns csv file

On 4/4/2008 8:51 AM, pk wrote:
> Ed Morton wrote:
> 
> 
>>No, if your input data looks like a number, it'll be considered to be a
>>number. Note that that only applies to input data so if "75" appears in
>>your input, it's a number, but if you explicitly use "75" in your code,
>>it's a string, and if "bob" appears in your input, that's also a string.
> 
> 
> Thanks. What put me on the wrong track was the fact that if you do
"print a"
> and a is uninitialized, it prints nothing since it considers a to have
the
> value ""

Depends if by "it" in "it considers.." you mean "print" or "awk".

Awk considers "a" to have the value 0 or "" depending on the context in
which
you use it, just like with input data. "print" prints strings. A numeric
argument is converted to a string before printing, so printing an
uninitialised
variable (which can be a string or a numeric) using print (which prints
strings)
means that the variable is taken to be a string IN THAT CONTEXT.

So "print" considers a to have the value "" but "awk" still considers a to
have
the value "" or 0.

> (you have to use a+0 to print 0), hence my "strings by default"
> thought. But of course, this has almost nothing to do with what happens
> during comparisons.
> Thanks

Yeah, there's a lot to think about when dealing with string/numeric
conversions
and comparisons using variables vs explicit strings vs explicit numbers vs
input
data. Even if you understand it at the time, it's often best to write your
code
to force explicit conversions so it's clearer later...

	Ed.