View source for IO type conversions

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Each output is of certain type and can pass its parameter if the "parameter override" field is left blank.

Possible output raw parameter types are: '''void''', '''integer''', '''float''', '''boolean''', '''string''', '''Vector''', '''color32''', variant or '''ehandle'''.
{{seealso|[[Data Descriptions#Field Types]]}}
{{wikinote|On entity pages more abstract types are used representing what values are supposed to be used. (for example material, target_source, filepath etc. are all '''string'''s)}}

== Possible conversions ==
{{note|Any non-'''string''' conversions can happen only if '''parameter override is left blank'''. Parameter override is always a '''string''' and therefore '''string''' conversion to whatever type the given input is will take place.}}

* If output and input parameter type match no conversion needed
* If output doesn't pass a parameter ('''void'''), then the input also must take no parameter ('''void''') or be of type '''string''' in which case empty '''string''' is used
* If output passes something and input takes no parameters ('''void''') we just give it nothing ('''void''').
* If output passes something and input takes a variant param we just pass it along. (this means that given input will be handling the conversion as it needs)
* If output passes '''integer''', then it can be converted to '''float''' or '''boolean'''.
* If output passes '''float''', then it can be converted to '''integer''' or '''boolean'''.
* If output passes '''string''', it will get converted to any type an input can be see below
* If output passes '''ehandle''', then it can be converted to '''string''' in which case it's converted to the '''ehandle''''s targetname

Otherwise conversion is invalid and we get the <code>"!! ERROR: bad input/output link:\n!!"</code> error

=== Conversion from '''string''' ===
* If '''string''' is being converted to '''integer'''/'''float''' it will take the leading portion of the '''string''' that makes sense as a number.
* If it's being converted to '''boolean''' it's first converted to '''integer''' and if it's 0 then it's false otherwise true.
<dd>{{example|
* <code>"54658"</code> is converted to '''integer''': 54685, '''float''': 54685.0, '''boolean''': true
* <code>"8593.55A99999"</code> is converted to '''integer''': 8593, '''float''': 8593.55, '''boolean''': true
* <code>"-89P13"</code> is converted to '''integer''': -89, '''float''': -89.0, '''boolean''': true
* <code>"X123456"</code> is converted to '''integer''': 0, '''float''': 0.0, '''boolean''': false
* <code>"true"</code> is converted to '''integer''': 0, '''float''': 0.0, '''boolean''': false
}}</dd>

* If '''string''' is being converted to '''color32''' it reads 4 values separated by spaces representing <code>"red green blue alpha"</code> (red,green,blue unspeicfied defaults to 0 alpha unspecified defaults to 255, going over 255 means overflow so using value like 1000 would really mean 1000 mod 256)
* If '''string''' is being converted to '''Vector''' it first tries to read 3 numbers enclosed in <code>[]</code> brackets i.e <code><code>"[x y z]"</code></code> and if that fails it tries <code><code>"x y z"</code></code>.
<dd>{{Example|
* <code>"142 25 0"</code> is converted to '''color32''': (r: 142, g: 25, b:0, a:255), '''Vector''': (x: 142.0, y: 25.0, z: 0.0)
* <code>"1000 400.5 4512 100"</code> is converted to '''color32''': (232, 144, 160, 100), '''Vector''': ( 1000.0, 400.5, 4512.0)
}}</dd>
* If '''string''' is being converted to '''ehandle''' it tries searching for the entity with the given targetname. !activator/!caller/!self are unusable here but other [[targetname#Keywords|special targetnames]] still work{{confirm}} like !player, !pvsplayer, !rochelle

== ERROR: bad input/output link examples ==

=== material_modfy_control ===
For example using {{ent|math_counter}} and in it defining the following output firing to {{ent|material_modify_control}}
<pre>OutValue
some_material_modify_control
SetMaterialVar
123.456</pre>
Will work without issues as SetMatrialVar takes '''string''' and parameter override is always '''string'''.
But if we actually tried passing the OutValue's value which is of type '''float''' 
<pre>OutValue
some_material_modify_control
SetMaterialVar
<left blank>
</pre>
then it won't work as conversion from '''float''' to '''string''' is not defined and we get "!! ERROR: bad input/output link:\n!!"

=== FireUserX ===
FireUser1-4 inputs have an unused '''string''' parameter. This causes issues in cases when an output passes some value that cannot be converted to '''string''' and parameter override is left empty. For example we use OnHealthChanged input of {{ent|prop_physics}} making it do FireUser1.
<pre>OnHealthChanged
some_entity
FireUser1
<parameter left blank>
</pre>
OnHealthChanged will try to pass '''float''' value to FireUser1 which is of type '''string''' therefore causing "!! ERROR: bad input/output link:\n!!".

== See also ==
* {{ent|material_modify_control}} - its inputs take '''string''' and conversion to '''string''' is only possible from '''string''' or '''ehandle'''
* [[User Inputs and Outputs]] - see FireUserX warning
* [https://github.com/ValveSoftware/source-sdk-2013/blob/0565403b153dfcde602f6f58d8f4d13483696a13/src/game/server/cbase.cpp#L1390 variant_t::Convert]