Master C# Programming From Scratch

Operators

An operator in C# is a symbol that tells the compiler to perform specific mathematical, logical, or data manipulations on operands (variables or values).

C# provides a rich set of built-in operators. Below are the primary categories of C# Operators.

1. Arithmetic Operators

   Used to perform common mathematical computations on numeric types.

   • + (Addition): Adds two values.
   • - (Subtraction): Subtracts one value from another.
   • * (Multiplication): Multiplies two values.
   • / (Division): Divides one value by another.
   • % (Modulus): Returns the division remainder.

   Example

   C#

   using System;
    
   int a = 10;
   int b = 3;
   
   Console.WriteLine(a + b);  // Output: 13
   Console.WriteLine(a - b);  // Output: 7
   Console.WriteLine(a * b);  // Output: 30
   Console.WriteLine(a / b);  // Output: 3 (Integer division drops decimal part)
   Console.WriteLine(a % b);  // Output: 1 (Remainder of 10 / 3)

   Try It

   Important: When two integer values are divided, C# performs integer division and the decimal part is removed.

2. Relational (Comparison) Operators

   Used to compare two values. These always return a boolean result (true or false).

   • == (Equal to): Checks if two values are equal.
   • != (Not equal to): Checks if two values are not equal.
   • > (Greater than): Checks if the left value is greater than the right.
   • < (Less than): Checks if the left value is less than the right.
   • >= (Greater than or equal to): Checks left value is greater than or equal to the right.
   • <= (Less than or equal to): Checks left value is less than or equal to the right.

   Example

   C#

   using System;
    
   int x = 5;
   int y = 10;
   
   Console.WriteLine(x == y); // Output: False
   Console.WriteLine(x != y); // Output: True
   Console.WriteLine(x > y);  // Output: False
   Console.WriteLine(x < y);  // Output: True
   Console.WriteLine(x >= 5); // Output: True

   Try It

   Example: Comparison operators are commonly used when checking age, marks, salary, eligibility, or other conditions.

3. Logical Operators

   Used to combine multiple boolean conditions or expressions.

   • && (Logical AND): Returns true if both statements are true.
   • || (Logical OR): Returns true if at least one statement is true.
   • ! (Logical NOT): Reverses the logical state (turns true to false and vice versa).

   Example

   C#

   using System;
    
   bool isSunny = true;
   bool isWarm = false;
   
   Console.WriteLine(isSunny && isWarm); // Output: False
   Console.WriteLine(isSunny || isWarm);  // Output: True
   Console.WriteLine(!isSunny);           // Output: False

   Try It

   Real-World Example: Logical operators can be used to check multiple conditions, such as username/password validation or age and eligibility conditions.

4. Assignment Operators

   Used to assign values to variables. This includes compound assignments which combine arithmetic operations with an assignment.

   • = (Simple Assignment): Assigns right value to left variable.
   • += (Add and assign): Shorthand for x = x + y.
   • -= (Subtract and assign): Shorthand for x = x - y.
   • *= (Multiply and assign): Shorthand for x = x * y.
   • /= (Divide and assign): Shorthand for x = x / y.

   Example

   C#

   using System;
    
   int score = 10; // Simple assignment
   
   score += 5; // Equivalent to score = score + 5; (score is now 15)
   score -= 2; // Equivalent to score = score - 2; (score is now 13)
   score *= 2; // Equivalent to score = score * 2; (score is now 26)
   
   Console.WriteLine(score); // Output: 26

   Try It

5. Increment and Decrement Operators

   Unary operators used to increase or decrease a variable's value by exactly 1.

   • ++ (Increment): Increases value by 1.
   • -- (Decrement): Decreases value by 1.

   Example

   C#

   using System;
    
   int energy = 5;
   
   energy++; // Postfix increment (energy becomes 6)
   Console.WriteLine(energy); // Output: 6
   
   --energy; // Prefix decrement (energy becomes 5)
   Console.WriteLine(energy); // Output: 5

   Try It

   Note: Both ++ and -- change the variable value by exactly one.

6. Ternary (Conditional) Operator

   A shorthand alternative to the if-else statement. It operates on three operands: condition ? expression_if_true : expression_if_false

   Example

   C#

   using System;
    
   int age = 20;
   
   string status = (age >= 18) ? "Adult" : "Minor";
   
   Console.WriteLine(status); // Output: Adult

   Try It

   Tip: The ternary operator is useful when a simple condition needs to return one of two values.

7. Null-Coalescing Operators

   Operators designed to cleanly handle variables that might hold null values.

   • ??: Returns the left-hand operand if it is not null; otherwise, it returns the right-hand operand.
   • ??=: Assigns the right-hand value to the left-hand variable only if the left-hand variable is currently null.

   Example

   C#

   using System;
    
   string? name = null;
   
   // Use fallback if name is null
   string displayName = name ?? "Guest";
   
   Console.WriteLine(displayName); // Output: Guest
   
   // Assign value only if null
   name ??= "Alice";
   
   Console.WriteLine(name); // Output: Alice

   Try It

   Real-World Use: Null-coalescing operators are useful when displaying default values when a database field, user input, or optional value is null.

using System;
 
int marks = 75;
bool attendance = true;

bool eligible = marks >= 60 && attendance;

string result = eligible ? "Eligible" : "Not Eligible";

Console.WriteLine(result); // Output: Eligible