Comparaison between 2 strings

[fxblabview]

Good afternoon,

I have a question about the comparition between 2 strings.

My VI write in a txt file a message to indicate the state of the test. If this state is unchange I don't want to write on this file that's why I test the message and the message write in the last line of the txt file to be sure they are not similar and write.

But the comparator tools I use don't give the expected solution.

Someone could explain me how compaire these 2 strings?

Thanks

[altenbach]

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@fxblabview wrote:

But the comparator tools I use don't give the expected solution.

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• Attach code instead of pictures
• Look for differences in hidden characters (e.g. CR, vs LF, vs CRLF).
• If the result is not as expected, you need to tell us what you expect!

[altenbach]

To detect successive duplicate messages, use a feedback node and compare current and previous.

[billko]

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@fxblabview wrote:

Good afternoon,

I have a question about the comparition between 2 strings.

My VI write in a txt file a message to indicate the state of the test. If this state is unchange I don't want to write on this file that's why I test the message and the message write in the last line of the txt file to be sure they are not similar and write.

But the comparator tools I use don't give the expected solution.

Someone could explain me how compaire these 2 strings?

Thanks

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You send the strings with CR as your EOL but your read is set to convert EOL.  In Windows, EOL is CR + LF, so the changes the EOL and the strings no longer match.  It's only a guess (but a good one) since you didn't supply real code, and the probes and stuff don't show the backslash codes.

[tyk007 · Accepted solution]

Since you only really care about the "readable" string content perhaps you could use the Trim Whitespace node on both before comparing them?

[fxblabview]

Right the txt file replace my CR by an EOL. Thats why I should put a supplementary character on the reading to have complete sentence.

Thanks for your help.

[fxblabview]

It's a good solution to not be bored by these invisible types.

[GerdW]

Hi fx,

It's a good solution

The better solution would be to store the previous message in a feedback node for comparison: ne need to read the file before writing to it! (As has been suggested before!)

Simple like this:

[fxblabview]

Sorry Knight to my approximations about my first post on the forum.

My expected response was that the comparator tools give a false response when the 2 sentences tested were similar... and a true when they were different.

[GerdW]

Hi fx,

My expected response was that the comparator tools give a false response when the 2 sentences tested were similar... and a true when they were different.

The "unequal?" comparison gives TRUE when the inputs are unequal (aka "not the same").

When you are talking about this "unequal?" comparison then your expectation was right. 😄