C# If Else

Conditions and Decisions

A condition is any expression that evaluates to a Boolean value, either true or false. C# gives you a set of conditional statements that let you branch your code based on these values. The most common one is the if statement.

• Use if to run code only when a condition is true.
• Use else to run code when that condition is false.
• Use else if to test a new condition when the previous ones were false.
• Use the ternary operator (?:) as a short way to choose between two values.

The if Statement

The if statement runs a block of code only when its condition is true. Notice the condition sits inside parentheses, and the code to run sits inside curly braces.

int temperature = 30;

if (temperature > 25)
{
    Console.WriteLine("It is a warm day.");
}

The else and else if Statements

Use else to define a block that runs when the if condition is false. Add else if between them to test extra conditions in order. C# checks each condition from top to bottom and runs the first block whose condition is true.

int score = 72;

if (score >= 90)
{
    Console.WriteLine("Grade: A");
}
else if (score >= 60)
{
    Console.WriteLine("Grade: B");
}
else
{
    Console.WriteLine("Grade: F");
}

The Ternary Operator

When you only need to choose between two values, the ternary operator gives you a compact one-line version of if...else. It follows the pattern condition ? valueIfTrue : valueIfFalse.

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