Help w/variables

Hi there. I am currently working on a 3d platformer/adventure game in Unity. I have implemented the three basic scripts, but I am having some trouble with having certain terrain "damage" the player.

What I mean to say is: There variable for the damage is assigned, but its value is never used. Here are the scripts I'm using:

using UnityEngine; using UnityEngine.UI; using System.Collections;

public class Healthbar : MonoBehaviour

{ public Image currentHealthbar; public Text ratioText;

 private float hitpoint = 150;
 private float maxHitpoint = 150;

 private void Start()
 {
     UpdateHealthbar ();
 }

 private void UpdateHealthbar()
 {
     float ratio = hitpoint / maxHitpoint;
     currentHealthbar.rectTransform.localScale = new Vector3 (ratio, 1, 1);
     ratioText.text = (ratio * 100).ToString("0") + '%';
 }

 private void TakeDamage(float damage)
 {
     hitpoint -= damage;
     if (hitpoint < 0) 
     {
         hitpoint = 0;
         Debug.Log ("Dead!");
     }

     UpdateHealthbar ();
 }

 private void HealDamage(float heal)
 {
     hitpoint += heal;
     if (hitpoint > maxHitpoint)
         hitpoint = maxHitpoint;

     UpdateHealthbar ();
 }

}

using System.Collections; using System.Collections.Generic; using UnityEngine;

public class Fighter : MonoBehaviour {

 private CharacterController controller;
 private Vector3 moveVector;
 private float verticalVelocity;

 public Collider[] attackHitboxes;

 private void Start()
 {
     controller = GetComponent<CharacterController>();
 }

 private void Update()
 {
     if (Input.GetButtonDown ("A"))
         LaunchAttack (attackHitboxes [0]);
     if (Input.GetButtonDown ("Z"))
         LaunchAttack (attackHitboxes [1]);

     if(controller.isGrounded)
     {
         verticalVelocity = -1;

         if(Input.GetButtonDown("Jump"))
             verticalVelocity = 10;
     }
     else
     {
         verticalVelocity -= 14 * Time.deltaTime;
     }

     moveVector = Vector3.zero;
     moveVector.x = Input.GetAxis("Horizontal") * 5;
     moveVector.y = verticalVelocity;

     controller.Move(moveVector * Time.deltaTime);
 }

 private void LaunchAttack (Collider col)
 {
     Collider[] cols = Physics.OverlapBox (col.bounds.center, col.bounds.extents, col.transform.rotation, LayerMask.GetMask ("Hitbox"));
     foreach (Collider c in cols) {
         if (c.transform.parent.parent == transform)
             continue;

         float damage = 0;
         switch (c.name) {
         case "Head":
             damage = 30;
             break;
         case "Torso":
             damage = 10;
             break;

         }
     }
 }

}

using UnityEngine; using System.Collections;

public class FloorTriggerZone : MonoBehaviour

{ public bool isDamaging; public float damage = 10;

 private void OnTriggerStay(Collider col)
 {
     if(col.tag == "Player")
         col.SendMessage((isDamaging)?"TakeDamage":"HealDamage",Time.deltaTime * damage);
 }

}

Also if anyone is wondering where I got the scripting from: https://www.youtube.com/watch?v=mvVM1RB4HXk&t=1402s

Any help would be appreciated -- thank you!