Comparison and Logical Operators

Comparison Operators

Compare two values and return true or false. Used in Unity to compare player health, score, level, etc.

Size Comparison

• > : true if left is greater

  • Example: playerHp > 0 → true if health is greater than 0 (alive)
  • Example: currentScore > highScore → true if current score is higher than high score

• < : true if left is less

  • Example: enemyHp < 10 → true if enemy health is less than 10 (weak state)
  • Example: playerLevel < maxLevel → true if player level is below max level

Equality Comparison

• == : true if two values are equal

  • Example: playerHp == 0 → true if health is 0 (dead)
  • Example: itemCount == maxInventorySize → true if item count equals max inventory size

• != : true if two values are different

  • Example: playerHp != 0 → true if health is not 0 (alive)
  • Example: currentWeapon != null → true if current weapon exists

Greater or Equal, Less or Equal

• <= : true if left is less than or equal to right

  • Example: playerHp <= 30 → true if health is 30 or below (danger state)
  • Example: enemyCount <= 0 → true if there are no enemies or count is 0

• >= : true if left is greater than or equal to right

  • Example: playerLevel >= 10 → true if level is 10 or above (can level up)
  • Example: score >= targetScore → true if score meets or exceeds target score

Logical Operators

Used to combine multiple conditions. Essential for creating complex game logic in Unity.

OR Operator (||)

• Meaning: "or" - true if at least one is true
• Game example:

// If player is dead or game is over
if (playerHp <= 0 || isGameOver)
{
    ShowGameOverScreen();
}

// Jump if spacebar or left mouse button is pressed
if (Input.GetKeyDown(KeyCode.Space) || Input.GetMouseButtonDown(0))
{
    Jump();
}

Unity usage:

• Check if any of multiple input keys are pressed
• Execute if any of multiple conditions are met
• Player is dead or time ran out, etc.

AND Operator (&&)

• Meaning: "and" - true only if both are true
• Game example:

// Can use skill if health exists and mana is sufficient
if (playerHp > 0 && playerMana >= skillCost)
{
    UseSkill();
}

// Give reward if level is 10+ and quest is completed
if (playerLevel >= 10 && questCompleted)
{
    GiveReward();
}

Unity usage:

• Execute only when all conditions are met
• Check if item can be used (item exists, no cooldown, etc.)
• Check if boss can be defeated (weapon exists, health exists, etc.)

NOT Operator (!)

• Meaning: "not" - converts true to false, false to true
• Game example:

// Continue playing if game is not over
if (!isGameOver)
{
    UpdateGame();
}

// Can attack if weapon is not null (weapon exists)
if (!(currentWeapon == null))
{
    Attack();
}

// Or more simply
if (currentWeapon != null)
{
    Attack();
}

Unity usage:

• Invert conditions
• Opposite of null check
• Execute when game state is not something

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