"=" or "==", I don't understand...

[Imbuter2000]

Should I expect the message "yes" or "no" from the following code?

local $value = 0
if $value = "abcdef" Then
    msgbox(0,"","yes")
else
    msgbox(0,"","no")
endif

Note: $value can contain both numbers or texts in my program and I want the test to be Case insensitive...

[JLogan3o13]

Take a look at the Operators entry in the help file. It explains the difference perfectly.

[guinness]

Yes as it interprets "abcdef" being a number. Use == instead.

[Imbuter2000]

"==" is case sensitive and as I wrote I would it case insensitive.

I read the help page lot of times but I still doesn't understand why it interprets "abcdef" as 0!

= Tests if two values are equal. e.g. If $var= 5 Then (true if $var equals 5). Case insensitive when used with strings. == Tests if two strings are equal. Case sensitive. The left and right values are converted to strings if they are not strings already. This operator should only be used for string comparisons that need to be case sensitive.

[water]

When you compare a string and a number using the "=" operator then AutoIt converts the string to a number. "abcdef" does not start with an integer and hence is translated to 0.

Try this:

ConsoleWrite(Number("abcdef") & @LF)
ConsoleWrite(Number("4abcdef") & @LF)
ConsoleWrite(Number("abcd4ef") & @LF)

[Imbuter2000]

When you compare a string and a number using the "=" operator then AutoIt converts the string to a number. "abcdef" does not start with an integer and hence is translated to 0.

Is it written in the help page? (I'll likely forget it in a few months...)

[water]

Here: "If a string is used as a number, an implicit call to Number() function is done. So if it doesn't contain a valid number, it will be assumed to equal 0."

[iamtheky]

So, if wanting to do a case insensitive comparison of a variable that could either be a string or a number, what is the correct way? i think this works, but i know there has to be a cleaner method

local $value = 0

If isnumber($value) Then

if $value == "abcdef" Then
msgbox(0,"","yes")
else
msgbox(0,"","no")
endif

Else

if $value = "abcdef" Then
msgbox(0,"","yes")
else
msgbox(0,"","no")
endif
[size=4]Endif[/size]

Edited January 24, 2013 by boththose

[guinness]

Is it written in the help page? (I'll likely forget it in a few months...)

Please don't.

[BrewManNH]

How about this:

Local $Value = 0
IsEqual($Value)
IsEqual("ABCDEF")
Func IsEqual($vValue)
     If String($vValue) = "abcdef" Then
          MsgBox(0, "", "yes")
     Else
          MsgBox(0, "", "no")
     EndIf
EndFunc   ;==>IsEqual

Convert the incoming string to a string, then compare it to the string in the function.

[JohnQSmith]

Note: $value can contain both numbers or texts in my program and I want the test to be Case insensitive...

local $value = 0
if StringCompare($value,"abcdef") = 0 Then
    msgbox(0,"","yes")
else
    msgbox(0,"","no")
endif

[Imbuter2000]

Here: "If a string is used as a number, an implicit call to Number() function is done. So if it doesn't contain a valid number, it will be assumed to equal 0."

hmmm but I didn't want the string to be used as a number... the most logical thought I did was that a string (different than the number) is NOT equal to a number... so simple.... is this AutoIT automatic conversion written in the help too? I think that it should... primarily in the "=" description of the "Language Reference - Operators" page...

Also consider this:

local $value = 1

if $value = string($value) Then
    msgbox(0,"","yes")
else
    msgbox(0,"","no")
endif

This code display "yes", so AutoIT didn't decide to use the string as a number in this different case of number-vs-string comparison....

[BrewManNH]

You're comparing a number with a string, so the string is converted back to a number even though you told it to make it a string. Number("1") = 1.

[guinness]

I might be throwing confusion into the mix:

#include <Constants.au3>

Local $vValue = 1
MsgBox($MB_SYSTEMMODAL, 'IsString', IsString(String($vValue)) = 1)

If $vValue <> String($vValue) Then
    MsgBox($MB_SYSTEMMODAL, '', 'Yes')
Else
    MsgBox($MB_SYSTEMMODAL, '', 'No')
EndIf

[kylomas]

imputer2000,

is this AutoIT automatic conversion written in the help too? I think that it should... primarily in the "=" description of the "Language Reference - Operators" page...

Water pointed you to the correct doc in post # 7. However, I will agree that a reference to water's link in the "operator" sectiond would'nt hurt.

kylomas

[Imbuter2000]

You're comparing a number with a string, so the string is converted back to a number even though you told it to make it a string. Number("1") = 1.

Ah, you're right

Water pointed you to the correct doc in post # 7. However, I will agree that a reference to water's link in the "operator" sectiond would'nt hurt.

At this point I agree with this conclusion

[Spiff59]

I've started a thread or two since Jan 2009 about better documenting the == operator. I've probably also posted in a dozen other threads trying to assist members asking this same question. The docs used to say only that "=" was case-sensitive and that "==" was case-insensitive. The wording was expanded a little, but I think it still lacks clarity. Stating that "This operator should only be used for string comparisons that need to be case sensitive" is incorrect as the == operator is very useful when trying to compare any of the following:

- A numeric zero: 0

- A string zero: "0" or Chr(48)

- An empty string: ""

- A null character: Chr(0)

- Boolean False

The = operator will accept any 2 of the above values as being equivalent.

The == operator can discern between all 5 entities above, accepting no 2 as being equal. I've found the operator useful to differentiate between an empty string and a zero more than once. That's not really a comparison that falls under the "case-dependant string comparison" umbrella.

[nitekram]

I've started a thread or two since Jan 2009 about better documenting the == operator. I've probably also posted in a dozen other threads trying to assist members asking this same question. The docs used to say only that "=" was case-sensitive and that "==" was case-insensitive. The wording was expanded a little, but I think it still lacks clarity. Stating that "This operator should only be used for string comparisons that need to be case sensitive" is incorrect as the == operator is very useful when trying to compare any of the following:

- A numeric zero: 0

- A string zero: "0" or Chr(48)

- An empty string: ""

- A null character: Chr(0)

- Boolean False

The = operator will accept any 2 of the above values as being equivalent.

The == operator can discern between all 5 entities above, accepting no 2 as being equal. I've found the operator useful to differentiate between an empty string and a zero more than once. That's not really a comparison that falls under the "case-dependant string comparison" umbrella.

Maybe get this to the powers to be and have it added ?

[kylomas]

@spiff59,

Can you clarify this wording

The = operator will accept any 2 of the above values as being equivalent.

. If "any two" will work then all will work as they can all be represented using the combination of "any two".

Apologies if I am nitpicking this...

kylomas

[guinness]

Who are the powers that be? Also there appears to be another mistake in your wording. My suggestion is re-write it how is should be and post in the appropriate help file thread. Thanks.