Re: about the use of button
- To: mathgroup at smc.vnet.net
- Subject: [mg115241] Re: about the use of button
- From: DrMajorBob <btreat1 at austin.rr.com>
- Date: Tue, 4 Jan 2011 18:51:54 -0500 (EST)
Clicking the button gives an error message:
carWeight == tareWeight;
personNumber == 0;
Row[{Button["A person enters", {carWeight += 60, personNumber++}],
Dynamic[{carWeight, personNumber}]}]
AddTo::rvalue: carWeight is not a variable with a value, so its value
cannot be changed. >>
Increment::rvalue: personNumber is not a variable with a value, so its
value cannot be changed. >>
Bobby
On Tue, 04 Jan 2011 03:26:40 -0600, W. Craig Carter <ccarter at mit.edu>
wrote:
> Hello Yang,
> Try this:
>
> ----
>
> carWeight == tareWeight;
> personNumber == 0;
>
> Row[{Button["A person enters", {carWeight +== 60, personNumber++}],
> Dynamic[{carWeight, personNumber}]}]
>
> -----
>
> You must avoid underscores "_" in variable names. It is a good habit to
> use an lower case letter to begin each variable name. Notice that
> Dynamic sits outside the button--that is the only place you need to see
> the current (i. e., dynamic) values.
>
> Craig
>
>
> On 28 Dec, 2010, at 6:51 AM, yang wrote:
>
>> Button["A person enters",
>> {Dynamic[car_weight+==60],Dynamic[person_number++}]]
>
>
--
DrMajorBob at yahoo.com