Program Structure & Sequence

A program is a sequence of instructions

Computers are very literal. If you give them several instructions, the order matters.

A sequence is simply the set of steps the program should run. Unless something changes the flow, the computer starts at the top and works downward.

• Create a value.
• Change the value.
• Display the result.

Give the sequence a name

SEQUENCE groups the instructions that make up our program.

SEQUENCE Start
    CREATE score AS 0
    CHANGE score TO 10
    SHOW score
END SEQUENCE

The same idea in Python

Python often puts the main sequence in a function named main and calls it when the file runs directly.

def main():
    score = 0
    score = 10
    print(score)

if __name__ == "__main__":
    main()

The same idea in JavaScript

A small JavaScript file can simply execute its statements from top to bottom.

let score = 0;
score = 10;
console.log(score);

The same idea in C#

A traditional C# console program starts in Main.

class Program
{
    static void Main()
    {
        int score = 0;
        score = 10;
        Console.WriteLine(score);
    }
}

The same idea in Java

A Java application starts in its main method.

public class Program {
    public static void main(String[] args) {
        int score = 0;
        score = 10;
        System.out.println(score);
    }
}

The same idea in C++

A C++ application begins execution in main().

int main()
{
    int score = 0;
    score = 10;
    std::cout << score << '\n';
    return 0;
}