How to check variable

Development Programming & Scripting Blueprint
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I am new to Unreal, and am used to a different visual scripting method. How do I check whether or not a variable is set? There doesn’t seem to be a “check variable” node.

What I want to do is “If variable is set then ___ happens”. Not sure how to translate that thought process to Unreal.

For example, I want different drop down menu options to do different things when selected. How do I make sure a SPECIFIC option is selected, and that SPECIFIC option is creating a result? I tried making it to where a specific UI element, when selected, printed “Hello”. All UI elements printed it though, no matter what I selected.

Again, I am very new. So I apologize. Pictures or examples would be helpful.

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You’re looking for the Switch node. There are multiple kinds, in this case you can use Switch on String or Switch on Int.

Switch on String:
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Select the Switch Node and in the Details panel, you can add Pin Names. If the selected option is the same as the Pin Name, that pin will get fired.

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Switch on Int

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There is also the Branch node if you want to check any conditions:

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1 Like
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Usually variables have default values so even though you didn’t set their value to something else, they’re already set to something. If by that you mean how to check if variables are not null, you can use the “Is Valid” node (with the question mark)

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This worked. Alternatively, if you have a number variable, how do you check that? For example, if you have a health bar. How do you do “Check if HP is 0. If 0 then ___”.

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Hey there @ImagineTheEnding! Welcome back to the community! If you’re comparing something like a float for health, you can use nodes like this:

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Hi!

What is the point of the == node? Does it just mean that if HP is at 0, nothing happens?

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There are a few different ways of assigning a variable a value based off of conditions, I believe they’ve all been mentioned above. The " select" decision would be one, you also have branch decision Wich execute a branch of your graph based off of a boolean value. To verify a variable holds a value, you could use an “is valid” check if it’s a reference to an object or class, or if simply a number or string type variable you can call “print” at the point in your graph your wanting to verify it has a value

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In the example I showed, I added the == node to show if you wanted to check for if it was 0 exactly instead, it’s not actually hooked up there.

The execution in pseudo code is:

CheckHP event is called
Get the health
Compare health (in this case the one thats actually hooked up is the Less than or equal to <=
That node gives a true or false (boolean). If it’s less or equal, it’s true, otherwise it outputs false.
Then the branch node takes that boolean, and decides which way to continue the execution from CheckHP.

You could instead of checking <= you could check == for exactly 0. I only added it below to show your options. Does that make sense?

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Oh gotcha. Thanks for explaining further.

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No worries! Please don’t hesitate to ask if you have any questions or need help finding specific learning resources!