djc said:
I had seen 'x+=1' in an example batch script... I was wondering if that
meant: x = x + 1 like it does in other languages.
Yes, it does.
However I could not find a
list of operators in the windows help file... It must be there but I can't
find it?
set /?
The /A switch specifies that the string to the right of the equal sign
is a numerical expression that is evaluated. The expression evaluator
is pretty simple and supports the following operations, in decreasing
order of precedence:
() - grouping
! ~ - - unary operators
* / % - arithmetic operators
+ - - arithmetic operators
<< >> - logical shift
& - bitwise and
^ - bitwise exclusive or
| - bitwise or
= *= /= %= += -= - assignment
&= ^= |= <<= >>=
, - expression separator
If you use any of the logical or modulus operators, you will need to
enclose the expression string in quotes. Any non-numeric strings in the
expression are treated as environment variable names whose values are
converted to numbers before using them. If an environment variable name
is specified but is not defined in the current environment, then a value
of zero is used. This allows you to do arithmetic with environment
variable values without having to type all those % signs to get their
values. If SET /A is executed from the command line outside of a
command script, then it displays the final value of the expression. The
assignment operator requires an environment variable name to the left of
the assignment operator. Numeric values are decimal numbers, unless
prefixed by 0x for hexadecimal numbers, and 0 for octal numbers.
So 0x12 is the same as 18 is the same as 022. Please note that the octal
notation can be confusing: 08 and 09 are not valid numbers because 8 and
9 are not valid octal digits.
