Null values for float, int and other numericals

Good day, and thanks for reading. I used float parameter of Animator component to control wich animation to play and such. But now i need to use sabe script for alot of same onjects, some of wich may not have that float declared in animatorcontroler. So question is - if i use GetFloat from animator and it doesn`t exist, what will i get? It won`t agree to compare to null because undeclared float is not a null and allweys returns true. But what w$$anonymous$$ll i get as a return from GetFloat if float i`m looking for is not even there?

             if(Anim.GetFloat("CurrentSpeed") //Some way to find if t$$anonymous$$s float exists in current animatorcontroller//)  
            {
                 Anim.SetFloat("CurrentSpeed", Speed); // Set float to current speed
             }

Thanks)