How to Handle Multiple Main Functions in C# and Java?

How does the compiler determine the entry point when there are multiple main functions across different classes in C# and Java?

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello World from HelloWorld!");
    }
}

public class AnotherClass {
    public static void main(String[] args) {
        System.out.println("Hello World from AnotherClass!");
    }
}

In C# and Java, the main function serves as the entry point for application execution. If you have multiple classes, each containing a main method, the compiler needs a way to know which main method to execute. Here's how it works for both languages:

// Compiling and Running in Java
// To run HelloWorld, use:
$ javac HelloWorld.java
$ java HelloWorld

// To run AnotherClass, use:
$ javac AnotherClass.java
$ java AnotherClass

// C# Example Configuration
// In a Visual Studio project, set the start-up object in project properties to the desired main class.

Causes

• Multiple classes can have their own main methods for testing or demonstrating functionality.
• The compiler does not automatically choose a main method; the programmer must indicate which main method to execute.

Solutions

• Specify the entry point when compiling or running the program if multiple main functions are present.
• In Java, use the command line to specify the class containing the main method. For example, `java HelloWorld` runs the main method in `HelloWorld` class.
• In C#, use the project settings or command line to set the start-up object to the desired class that contains the main method.

Mistake: Forgetting to specify which main method to run when multiple exist leads to confusion.

Solution: Clearly define the entry point in your IDE or command line.

Mistake: Confusion about which class's main method will run based on project configuration.

Solution: Always check project settings to confirm the chosen entry point.