Run and read a C# program

The idea

A C# source file contains instructions that the compiler checks before execution. These lessons use the top-level statement style supported by modern C#. The using System; line makes the System namespace available, and Console.WriteLine displays a value followed by a new line. A semicolon ends each simple statement.

A declaration connects a type, a name, and an initial value. string title = "Practice"; stores text, while int completed = 2; stores a whole number. A later assignment can replace the value without redeclaring the variable. C# distinguishes uppercase and lowercase names, so completed and Completed are different identifiers.

Read statements in order and predict each output before running the example in a C# environment. This course introduces types, arrays, methods, and classes in sequence; you do not need to know typed collections before this first program. The next chapter explains more numeric and string operations.

using System;
string title = "Practice";
int completed = 2;
Console.WriteLine(title);
Console.WriteLine(completed);
completed = completed + 1;
Console.WriteLine(completed);

Practice
2
3

The program prints the initial count, then prints its new value after the assignment adds one.