Match pattern string

[Vindhyachal.Takniki]

I have aattached VI. trying to make a basic calculator. (staretd making it, first I want to get correct string from user.)

When user enter decimal(.), it should not be able to enter decimal again.

I have made code in which a string match pattern is used to check if decimal is already present. if present then do not add it otherwise add it.

Although whenever I press decimal, match pattern always return true. Don't know why?

[Dennis_Knutson]

Why are you using a string for a numeric entry? That just seems like a Rube Goldberg.

[Dennis_Knutson]

Never mind. I see you want to use a keypad for numeric entry.

[Vindhyachal.Takniki]

I want to make a calculator as in windows. for learning purpose

[altenbach]

• The terminals of latch action buttons belong inside their respective event cases.
• The string belongs into a shift register. No need for local variables
• The character "." has a special meaning. You need to escape it. See the help. Use "\." as search term instead, then append "." to the string if needed.
• You can delete the timeout case.
• There is no event for the "2" button.

[Vindhyachal.Takniki]

I cannot use string roll over. Since I am making a calculator as in windows 10. Right now I am making standard version of calc as on windows(Alt+1 press on window calc to open standard version)

If I keep on entering string as such, then it can enter can alphabet A-z,0-9. 

In attached VI, currently I have made a part where user can enter string upto 16 places (as in window calc)

Now problem is string eneterd in my VI can be any for example: +0.968, +098.8, -9.89

Now I have to display 0.968,+98.8,-9.89 for above strings.

1. How to do that?

2. Currently I can enter numbers by clicking on VI butons only. How can I enter them by pressing button on keyboard also?

[Gregory]

You can use the Key Down event with a case structure: