C# Goto Statement

In this tutorial, we will explore the goto statement in C#. The goto statement is a form of control flow that allows you to unconditionally jump to a labeled statement within the same method. Although the use of goto is generally discouraged due to its potential to create spaghetti code and make the code harder to understand and maintain, there are cases where it can be useful, such as breaking out of nested loops or simplifying a state machine.

Basic Syntax

The goto statement has the following syntax:

goto label;

You need to have a labeled statement in your code where the control flow will jump to:

label:
    statement;

Using Goto

Here's an example of how to use the goto statement to jump between labeled statements:

int x = 5;

start:
if (x > 0)
{
    Console.WriteLine(x);
    x--;
    goto start;
}

Console.WriteLine("Finished counting down.");

In this example, we use a goto statement to jump to the start label until x is no longer greater than 0. The output will be:

5
4
3
2
1
Finished counting down.

Breaking Out of Nested Loops

One of the legitimate use cases for the goto statement is breaking out of nested loops. Here's an example:

int[,] matrix = new int[,]
{
    { 1, 2, 3 },
    { 4, 5, 6 },
    { 7, 8, 9 }
};

bool found = false;

for (int i = 0; i < 3; i++)
{
    for (int j = 0; j < 3; j++)
    {
        if (matrix[i, j] == 5)
        {
            found = true;
            Console.WriteLine($"Found 5 at ({i}, {j})");
            goto breakNestedLoops;
        }
    }
}

breakNestedLoops:
if (!found)
{
    Console.WriteLine("5 not found.");
}

In this example, we use a goto statement to break out of nested for loops as soon as we find the number 5 in the matrix.

Alternatives to Goto

In most cases, it is better to use structured control flow statements like if, else, while, for, and foreach instead of goto. You can also use methods to encapsulate control flow logic and return statements to exit early.

For example, the countdown example can be rewritten using a while loop:

int x = 5;

while (x > 0)
{
    Console.WriteLine(x);
    x--;
}

Console.WriteLine("Finished counting down.");

This tutorial demonstrates the basics of the goto statement in C#. While the goto statement can be useful in some situations, it should be used sparingly and with caution, as it can make your code more difficult to understand and maintain.

How to use goto in C#

Using goto in C# involves creating a label and jumping to that label using the goto keyword. Here's a simple example:

using System;

class Program
{
    static void Main()
    {
        int i = 0;

        // Define a label
        start:

        Console.WriteLine(i);

        i++;

        // Use goto to jump to the label
        if (i < 5)
            goto start;

        Console.ReadLine();
    }
}

C# labeled statements with goto

You can label statements to provide a target for the goto statement. Here's an example:

using System;

class Program
{
    static void Main()
    {
        int i = 0;

        // Define a labeled statement
        loopStart:

        Console.WriteLine(i);

        i++;

        if (i < 5)
            goto loopStart;

        Console.ReadLine();
    }
}