Csharp/CSharp Tutorial/String/String Format

Formatting Using the R Format Specifier

<source lang="csharp">class MainClass {

 static void Main()
 {
   const double number = 1.612;
   double result;
   string text;
   text = string.Format("{0}", number);
   result = double.Parse(text);
   System.Console.WriteLine("{0}: result != number",result != number);
   text = string.Format("{0:R}", number);
   result = double.Parse(text);
   System.Console.WriteLine("{0}: result == number",result == number);
 }

}</source>

.NET String Format Characters

<source lang="csharp">String Format Character Meaning in Life C or c format currency. D or d format decimal numbers. E or e Used for exponential notation. F or f Used for fixed-point formatting. G or g Stands for general. N or n numerical formatting. X or x hexadecimal formatting.</source>

String and WriteLine Format Specifiers

<source lang="csharp">Character Interpretation C or c Currency D or d Decimal E or e Exponent F or f Fixed point G or g General N or n Number; similar to F with the addition of comma thousand separators P or p Percentage R or r Round-trip X or x Hex</source>

String format: {0,3:D}, {1,8:D}

<source lang="csharp">using System;

class MainClass {

 public static void Main() {  
   int sum = 0, prod = 1;
   for(int i=1; i <= 10; i++) { 
     sum += i; 
     prod *= i; 
     string str = String.Format("Sum:{0,3:D}  Product:{1,8:D}", 
                         sum, prod); 
     Console.WriteLine(str); 
   } 
 } 

}</source>

Sum:  1  Product:       1
Sum:  3  Product:       2
Sum:  6  Product:       6
Sum: 10  Product:      24
Sum: 15  Product:     120
Sum: 21  Product:     720
Sum: 28  Product:    5040
Sum: 36  Product:   40320
Sum: 45  Product:  362880
Sum: 55  Product: 3628800

String format: {0:C}

<source lang="csharp">using System;

class MainClass {

 public static void Main(string[] args)
 {
   string formStr = null;
   formStr = string.Format("you had {0:C} in your account?", 99989.987);
   Console.WriteLine(formStr);    
 }

}</source>

you had $99,989.99 in your account?

Use String.Format() to format a value.

<source lang="csharp">using System;

class MainClass {

 public static void Main() {
   double v = 17688.65849;
   double v2 = 0.15;
   int x = 21;
   string str = String.Format("{0:F2}", v);  
   Console.WriteLine(str);  
   str = String.Format("{0:N5}", v);  
   Console.WriteLine(str);  
 
   str = String.Format("{0:e}", v);  
   Console.WriteLine(str);  
 
   str = String.Format("{0:r}", v);  
   Console.WriteLine(str);  
 
   str = String.Format("{0:p}", v2);  
   Console.WriteLine(str);  
 
   str = String.Format("{0:X}", x);  
   Console.WriteLine(str);  
   str = String.Format("{0:D12}", x);
   Console.WriteLine(str);  
   str = String.Format("{0:C}", 189.99);
   Console.WriteLine(str);
 }

}</source>

17688.66
17,688.65849
1.768866e+004
17688.65849
15.00 %
15
000000000021
$189.99

Use ToString to format double: C

<source lang="csharp">using System;

class MainClass {

 public static void Main() { 
   string str = 189.99.ToString("C"); 
   Console.WriteLine(str); 
 }

}</source>

$189.99