else and else if

Learn else and else if chains for alternative cases.

else and else if

To run a different block when the if condition is false you use else. For more branches you build an else if chain: the first true condition's block runs, the rest are skipped.

For example, letter grades use if (score >= 90) { ... } else if (score >= 80) { ... } else { ... }. The else at the end is the 'none of the above' branch and runs unconditionally.

Nested if and readability

You can write another if inside an if block; this is called a nested if. Deep nesting, however, hurts readability, so an else if chain or switch is preferred.

For example, if (logged && admin) { ... } reads better than if (logged) { if (admin) { ... } }. Keeping conditions flat where possible simplifies the code.

Exercise Determine the letter grade

Declare a score variable with the value 85. With if, else if and else: print "A" for 90 and above, "B" for 80 and above, "C" otherwise. A score of 85 should yield 'B'.

Show example solution

if (score >= 90), else if (score >= 80), else. Wrap each body in braces.
Example solution:
using System;

class Program
{
    static void Main()
    {
        int score = 85;
        if (score >= 90) { Console.WriteLine("A"); }
        else if (score >= 80) { Console.WriteLine("B"); }
        else { Console.WriteLine("C"); }
    }
}

Test yourself

Start the else branch

if (age >= 18) {
    Console.WriteLine("adult");
}
____ {
    Console.WriteLine("child");
}

Show answer

if (age >= 18) {
    Console.WriteLine("adult");
}
else {
    Console.WriteLine("child");
}

With int score = 75; which output is printed?

int score = 75;
if (score >= 90) Console.WriteLine("A");
else if (score >= 80) Console.WriteLine("B");
else Console.WriteLine("C");

A
B
C
Error

Show answer

C — Correct. 75 clears neither 90 nor 80; the else prints 'C'.

Match each branch to its meaning

if

First condition
else if

Alternative condition
else

Fallback branch
else if x3

Three-way chain

Next lesson: The switch statement

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