c# - How to check if a game object has a component method in Unity? -

i writing method check if gameobject has component.

here is:

public static bool hascomponent <t>(this gameobject obj) {     return obj.getcomponent<t>() != null; } 

and i'm using this:

void update() {      if (input.getkey("w"))     {         if (gameobject.hascomponent<rigidbody>())         {             print("has rigid body.");             return;         }          print("does not have rigid body.");     } } 

the gameobject not have rigid body still printing have.

it just...

public static bool hascomponent <t>(this gameobject obj) t:component     {     return obj.getcomponent<t>() != null;     } 

note forgot the

where t:component

part of first line!

with syntax error, extension meaningless: it's finding "some component" (since t sort of "blank") , hence never null. it's syntax error.

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note.

explanation of "what heck extension".

for reading not familiar categories in c# .. "extensions" in c# ... here's easy tutorial ...

extensions absolutely critical in unity - use them @ least once in every line of code. basically in unity in extension. note op did not bother showing wrapper class. you'd have in file this:

public static class extensionshandy // class name irrelevant , not used     {      public static bool hascomponent <t>(this gameobject obj) t:component         {         return obj.getcomponent<t>() != null;         }      public static bool isnear(this float ff, float target)         {         float difference = ff-target;         difference = mathf.abs(difference);         if ( difference < 20f ) return true;         else return false;         }      public static float jiggle(this float ff)         {         return ff * unityengine.random.range(0.9f,1.1f);         }      public static color colored( float alpha, int r, int g, int b )         {         return new color(             (float)r / 255f,             (float)g / 255f,             (float)b / 255f,             alpha );         }      } 

in example included 3 more typical extensions. you'd have dozens or hundreds of them. (you may prefer group them in different handyextensions files - file name of wrapper class totally irrelevant.) every engineer , team has own "common extensions" use time.

note here example example asking tricky question in category beyond me. (thank goodness ericl there!) way in most/some/older languages call "category". in c# "extension", people either "category" or "extension" time.

as say, use these in unity. cheers

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if sort of thing, here's beautiful one:

// unbelievably useful array handling category games!  public static t anyone<t>(this t[] ra) t:class     {     int k = ra.length;     int r = unityengine.random.range(0,k);     return ra[r];     }