Declaring Constants

Constants are similar to variables however their value is always set at the declaration time and cannot be changed later.

They are useful in making the code easier to understand by indicating which values do not and are not supposed to be changed throughout the program. Moreover, it minimizes accidental unwanted changes to the data hence reducing bugs in the code.

When declaring a constant we use a similar syntax to variable declaration but we add the keyword const before it:

main


              12345678910111213
            
using System;

namespace ConsoleApp
{
    internal class Program
    {
        static void Main(string[] args)
        {
			const int myVar = 10;
			Console.WriteLine(myVar);
        }
    }
}

If we try to modify a constant, the compiler will show an error:

main


              1234567891011121314
            
using System;

namespace ConsoleApp
{
    internal class Program
    {
        static void Main(string[] args)
        {
			const int myVar = 10;
			myVar = 20; 
          // Error: The left-hand side of an assignment must be a variable, property or indexer.
        }
    }
}

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Seção 2. Capítulo 10

C# Basics

Declaring Constants

Complete the code for declaring a constant called `pi` having a value of `3.14`: