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The Hello World Program

Lets create a simple Hello World! program which just prints the text Hello, World! to the CLI. But before we can do that we need to create an entry point for our Flint program.

The entry point of every Flint program is the main function. This function is reserved for the programs entry point, so no other function is allowed to be called main. The entry point of any program is the point where the program starts its execution. Any program works from top to bottom, and everything within the main function is executed first. You dont need to worry about functions yet, they are explained in a later chapter.

But, lets create the example first and then explain what actually happens afterwards:

use Core.print

def main():
    print("Hello, World!\n");

There is a lot to unpack here. You can safely ignore the use Core.print line for now. Just remember that this line needs to be written in order for the print function to be accessible. But what that line actually does will be described in a later chapter.

The def main(): line is the definition of the main function, but functions are described in a later chapter too.

Now we come to the interesting line. print("Hello, World!\n");. print is a function call. A function call is like an instruction to execute. In this case we tell the Flint program to print the text to the console thats written in between the " symbols. This text between the " symbols is called a string. Here, we tell the print function to print the string Hello, World!\n. But what is this \n character? Its an escaped character for a new line. The print function does not print a new line after the string, so we need to provide a newline character manually.

The output of the above program would look like this:

Hello, World!

Try to remove the \n character and see what it does for yourself!

Always remember: The best way to learn is to try new things. Your computer won't explode if you make mistakes in a program, so just try out a few things and see for yourself what works and what doesn't!