Sign in to follow this  
Followers 0
annelinn

Why does the expression < 0 = "hello" > evaluate to 'true'?

6 posts in this topic

Forgive a very stupid question...

If 0 = "hello" Then
    MsgBox(1, "0 is true")
EndIf

I always understood that 0 has the boolean value of false, and strings have the boolean value of true?

Share this post


Link to post
Share on other sites



annelinn,

0 is a number - all variables begin with $ - so 0 = "hello" changes nothing and means nothing.

"0 is true" is a literal string, so of course the MsgBox will display it just as it would display any other obviously untrue statement such as "Tony Blair did NOT lie to get the British to go to war in Iraq". Or at least it would if you got the MsgBox syntax right. ;)

In fact the whole code is complete garbage. :evil:

M23


Any of my own code posted anywhere on the forum is available for use by others without any restriction of any kind._______My UDFs:

Spoiler

ArrayMultiColSort ---- Sort arrays on multiple columns
ChooseFileFolder ---- Single and multiple selections from specified path treeview listing
Date_Time_Convert -- Easily convert date/time formats, including the language used
ExtMsgBox --------- A highly customisable replacement for MsgBox
GUIExtender -------- Extend and retract multiple sections within a GUI
GUIFrame ---------- Subdivide GUIs into many adjustable frames
GUIListViewEx ------- Insert, delete, move, drag, sort, edit and colour ListView items
GUITreeViewEx ------ Check/clear parent and child checkboxes in a TreeView
Marquee ----------- Scrolling tickertape GUIs
NoFocusLines ------- Remove the dotted focus lines from buttons, sliders, radios and checkboxes
Notify ------------- Small notifications on the edge of the display
Scrollbars ----------Automatically sized scrollbars with a single command
StringSize ---------- Automatically size controls to fit text
Toast -------------- Small GUIs which pop out of the notification area

 

Share this post


Link to post
Share on other sites

#3 ·  Posted (edited)

Ah, but my problem is in this situation, where $variable might be a string, or an integer:

If $variable = "hello" Then
   MsgBox(1, "found", "hello")
EndIf

Since AutoIt uses the same label for strings and integers ($variable), and since I can't necessarily control the data type of $variable, I would have expected that...

If $variable = "hello" Then

...would be true if $variable is the string "hello", and FALSE when $variable is the integer 0.

But clearly not.

Edited by annelinn

Share this post


Link to post
Share on other sites

The native AutoIt functions generally try to auto-retype the variables to match the function requirements. A string like "123" will be converted to an integer 123. A sting like "1.23" will be converted to a float. Non-number strings like "hello" convert to 0. Try it with Number() function. Because of this, 0 = "hello" is true because in trying to convert "hello" to a numeric, it becomes 0.

You got the right answer from spudw2k, use == vice =. See "Operators" and "Variables" in the help file.

;)


Valuater's AutoIt 1-2-3, Class... Is now in Session!For those who want somebody to write the script for them: RentACoder"Any technology distinguishable from magic is insufficiently advanced." -- Geek's corollary to Clarke's law

Share this post


Link to post
Share on other sites

Thank you, all. I had read the Datatypes help file, but I didn't spot == in the Operators help file.

Merry Xmas!

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0