C# For and Foreach Loops

How it works

A for loop puts initialization, continuation and update together. Its condition is checked before the body, allowing an empty traversal. foreach expresses a visit to each element without manual index arithmetic. Pick the form from the operation rather than treating one as universally better. When an algorithm changes a collection’s structure, ordinary enumeration may be invalidated; build a separate result or use an operation designed for removal.

Run it locally

Use the .NET 10 SDK with C# 14 in a separate console lab. Create an empty project once with dotnet new console --framework net10.0, then replace Program.cs with this complete source and add any supporting files shown. Keep only one lesson entry point in the project. C# does not currently run in Bhylu’s browser playground. Apache, PHP and MySQL are not needed.

dotnet build -p:LangVersion=14.0 -p:Nullable=enable -p:TreatWarningsAsErrors=true
dotnet run --no-build

Use the SDK’s project workflow; the review compiles against its matching reference assemblies and executes the results without external NuGet packages. File-writing examples belong in a private empty lab directory.

Download the complete C# source as Program.cs.

Example

using System;

internal static class Program
{
    private static void Main(string[] args)
    {
        for (int table = 1; table <= 3; table++) Console.WriteLine($"Table {table}");
        int[] places = { 2, 4, 3 };
        int total = 0;
        foreach (int count in places) total += count;
        Console.WriteLine($"Total: {total}");
    }
}

Expected result

Table 1
Table 2
Table 3
Total: 9

The first loop prints one-based labels. The second uses stored values directly and sums a small bounded fixture. An array’s valid indices run from zero through Length minus one. A loop using index <= Length adds an invalid iteration. Keep a total’s range in mind when the input is no longer a fixed small array.