Conditions in Unity

🔀 Conditions: if and else

In Unity (and in C# in general), the if statement lets you run a piece of code only when a certain condition is true. The else block runs if that condition is not met.

Inside the round brackets after if, we write a condition. This is an expression that gets evaluated and returns either true or false. If it’s true, the code inside the curly braces runs. If it’s false, that part is skipped — or the else runs if it’s provided.

using UnityEngine;

public class CSharpScript : MonoBehaviour
{
  int health = 10;

  // Start is called once when the object is initialized
  void Start()
  {

  }

  // Update is called once per frame
  void Update()
  {
    if (health > 0)
    {
      // Player is still alive
      Debug.Log("Get up and fight!");
    }
    else
    {
      // Player is dead
      Debug.Log("Game Over");
    }
  }
} 

Here we check if the health is greater than zero. If it is, we print a message saying the player is still in the fight. If not, it’s time to restart the level. This is how most logic in games works.

In Unity, it's very common to check boolean variables — such as isJumping, isDead, isGrounded. These are convenient because they clearly show whether something is happening or not.

using UnityEngine;

public class CSharpScript : MonoBehaviour
{
  bool isDead = true;

  // Start is called once when the object is initialized
  void Start()
  {

  }

  // Update is called once per frame
  void Update()
  {
    if (isDead)
    {
      // Character is dead
      Debug.Log("Game Over");
    }
  }
}

You can also nest conditions inside each other for multi-level checks. This is useful when an action depends on several things at once — for example, the character can only jump if they are on the ground and the jump key is pressed. Though in such cases, it might be simpler to use logical operators to combine everything into one line.

using UnityEngine;

public class CSharpScript : MonoBehaviour
{
  bool isGrounded = true;
  bool jumpKeyPressed = true;

  // Start is called once when the object is initialized
  void Start()
  {

  }

  // Update is called once per frame
  void Update()
  {
    // Nested conditions
    if (isGrounded)
    {
      if (jumpKeyPressed)
      {
        Debug.Log("Jump performed (nested if)");
      }
    }

    // Same result using a logical operator
    if (isGrounded && jumpKeyPressed)
    {
      Debug.Log("Jump performed (logical AND)");
    }
  }
}

🎚 The switch Statement — Choosing Between Options

When you have many possible values and want to choose an action depending on them, the switch statement is very convenient. It's like a menu: if one option is selected — do this, if another — do that.

Inside the round brackets after switch, we place a variable or expression whose value we want to check. Then come the cases — possible values for that expression. If one of them matches, the code inside that block runs. To stop the program from continuing to the next block, we write break; at the end of each case. If no cases match, the default block is executed.

using UnityEngine;

public class CSharpScript : MonoBehaviour
{
  string enemyType = "zombie";

  // Start is called once when the object is initialized
  void Start()
  {
    switch (enemyType)
    {
      case "zombie":
        Debug.Log("Zombie attacks!");
        break;

      case "robot":
        Debug.Log("Robot shoots!");
        break;

      case "ghost":
        Debug.Log("Ghost vanishes!");
        break;

      default:
        Debug.Log("Unknown enemy...");
        break;
    }
  }

  // Update is called once per frame
  void Update()
  {

  }
}

💡The break; command ends the current case. If you forget it, execution will continue into the next blocks, even if they don’t match. This is called fall-through. Sometimes it’s done on purpose, but more often it’s a mistake — and leads to unexpected results.