If vs. Switch Comparison

Part of the Logic & Flow section of Coddy's C# journey. Lesson 10 of 66.

C# provides two primary ways to handle multiple conditions: if-else statements and switch statements. Each has its strengths in different scenarios.

If-else statements are flexible and can handle any type of condition:

string grade = "B";

if (grade == "A")
{
    Console.WriteLine("Excellent");
}
else if (grade == "B")
{
    Console.WriteLine("Good");
}
else if (grade == "C")
{
    Console.WriteLine("Satisfactory");
}
else
{
    Console.WriteLine("Needs improvement");
}

Switch statements are cleaner when comparing a single variable against multiple constant values:

string grade = "B";

switch (grade)
{
    case "A":
        Console.WriteLine("Excellent");
        break;
    case "B":
        Console.WriteLine("Good");
        break;
    case "C":
        Console.WriteLine("Satisfactory");
        break;
    default:
        Console.WriteLine("Needs improvement");
        break;
}

Switch can group multiple cases together (fall-through) so they share the same outcome. Stack the case labels one after another with no code between them, and only one break at the end:

string grade = "B";

switch (grade)
{
    case "A":
    case "a":
        Console.WriteLine("Excellent - 4 points");
        break;
    case "B":
    case "b":
        Console.WriteLine("Good - 3 points");
        break;
    case "C":
    case "c":
        Console.WriteLine("Satisfactory - 2 points");
        break;
    default:
        Console.WriteLine("Needs improvement");
        break;
}

Here, both "B" and "b" fall through to the same block and print "Good - 3 points". This pattern is useful whenever you want uppercase and lowercase inputs, or any set of values, to produce the same result.

Switch can also group cases with different labels that share an outcome:

char dayCode = 'M';

switch (dayCode)
{
    case 'M':
        Console.WriteLine("Monday");
        break;
    case 'T':
        Console.WriteLine("Tuesday or Thursday");
        break;
    case 'W':
        Console.WriteLine("Wednesday");
        break;
    case 'F':
        Console.WriteLine("Friday");
        break;
    default:
        Console.WriteLine("Unknown day");
        break;
}

Challenge

Medium

Create a method called convertGradeToPoints that:

Takes a letter grade as a string parameter
Converts it to a numeric grade point using both switch and if-else approaches
The method should implement both approaches and return the result of the switch implementation
Use these grade conversions:
- "A" or "a" = 4
- "B" or "b" = 3
- "C" or "c" = 2
- "D" or "d" = 1
- "F" or "f" = 0
- Any other input = -1

Try it yourself

public class ConvertGradeToPoints
{
    // Implement the convertGradeToPoints method
    public static int convertGradeToPoints(string letterGrade)
    {
        // Write your code here
        
    }
}