Quick C# Programming Notes on String Formatting

Here is a few examples on the different ways to format strings when outputting data to the user. Computers usually store numbers without formatting.

Some of these notes will tell you the exact code you would need to make a computer’s “224” to be outputted as “$224” or “224 %”.

using System;

class FormattingNumbers
static void Main()
decimal theDecNumber = 12345.678m; //the “m” creates a literal of type decimal from a double
//Using the ToString Method
//the number in the format string is the precision specifier
Console.WriteLine(“No formatting: ” + theDecNumber.ToString());
Console.WriteLine(“Currency formatting: ” + theDecNumber.ToString(“C”));
Console.WriteLine(“Exponential formatting: ” + theDecNumber.ToString(“E”));
Console.WriteLine(“Fixed-point formatting: ” + theDecNumber.ToString(“F2”));
Console.WriteLine(“General formatting: ” + theDecNumber.ToString(“G”));
Console.WriteLine(“Number formatting to 2 decimal places: ” + theDecNumber.ToString(“N2”));
Console.WriteLine(“Number formatting to 3 decimal places: ” + theDecNumber.ToString(“N3”));
Console.WriteLine(“Number formatting to 4 decimal places: ” + theDecNumber.ToString(“N4”));
Console.WriteLine(“Percent formatting: ” + theDecNumber.ToString(“P0”));

int theIntNumber = 123456;
Console.WriteLine(“Hexidecimal formatting (for integers): {0} = {1}”, theIntNumber, theIntNumber.ToString(“X”));

double theDblNumber = 1234567890;
Console.WriteLine(“Custom formatting: {0} to US telephone {1}”, theDblNumber, theDblNumber.ToString( “(###) ### – ####” ));

//Keep console open if not run through command prompt
Console.Write(“\nPress Enter to Continue”);

John Sheehan has some very good tips and information on his blog. For archive purposes I have mirrored his .NET cheatsheet (download link here). Hope this helps you.

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