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BigInteger.ToString Method (String)

Converts the numeric value of the current BigInteger object to its equivalent string representation by using the specified format.

Namespace:  System.Numerics
Assembly:  System.Numerics (in System.Numerics.dll)

public string ToString(
	string format
)

Parameters

format
Type: System.String

A standard or custom numeric format string.

Return Value

Type: System.String
The string representation of the current BigInteger value in the format specified by the format parameter.

ExceptionCondition
FormatException

format is not a valid format string.

The ToString(String) method formats a BigInteger value in a specified format by using a NumberFormatInfo object that represents the conventions of the current culture. If you want to use the default ("G", or general) format or specify a different culture, use the other overloads of the ToString method, as follows:

To use format

For culture

Use the overload

Default ("G") format

Default (current) culture

ToString()

Default ("G") format

A specific culture

ToString(IFormatProvider)

A specific format

A specific culture

ToString(String, IFormatProvider)

The format parameter can be any valid standard numeric format specifier, or any combination of custom numeric format specifiers. If format is equal to String.Empty or is null, the return value of the current BigInteger object is formatted with the general format specifier ("G"). If format is any other value, the method throws a FormatException.

In most cases, the ToString method supports 50 decimal digits of precision. That is, if the BigInteger value has more than 50 digits, only the 50 most significant digits are preserved in the output string; all other digits are replaced with zeros. However, BigInteger supports the "R" standard format specifier, which is intended to round-trip numeric values. The string returned by the ToString(String) method with the "R" format string preserves the whole BigInteger value and can then be parsed with the Parse or TryParse method to restore its original value without any loss of data. The following example illustrates that a string output using the "R" format string can then be parsed by the Parse method without any data loss.

// Create number with 50+ digits and store it to two strings.
BigInteger originalNumber = BigInteger.Pow(UInt64.MaxValue, Byte.MaxValue);
string generalString = originalNumber.ToString("G");
string roundTripString = originalNumber.ToString("R");
Console.WriteLine("The original value has {0} hexadecmal digits.\n", 
                  originalNumber.ToString("X").Length);

// Attempt to round-trip strings and compare them with the original.
Console.WriteLine("Parsing the string formatted with the 'G' format string.");
BigInteger generalBigInteger = BigInteger.Parse(generalString, 
                               NumberStyles.AllowExponent | NumberStyles.AllowDecimalPoint);
if (originalNumber.Equals(generalBigInteger))
   Console.WriteLine("The values are equal. No data has been lost.\n");
else            
   Console.WriteLine("The values are not equal. Data has been lost.\n");

Console.WriteLine("Parsing the string formatted with the 'R' format string.");
BigInteger roundTripBigInteger = BigInteger.Parse(roundTripString);
if (originalNumber.Equals(roundTripBigInteger))
   Console.WriteLine("The values are equal. No data has been lost.\n");
else            
   Console.WriteLine("The values are not equal. Data has been lost.\n");
// The example displays the following output: 
//       The original value has 4080 hexadecmal digits. 
//        
//       Parsing the string formatted with the 'G' format string. 
//       The values are not equal. Data has been lost. 
//        
//       Parsing the string formatted with the 'R' format string. 
//       The values are equal. No data has been lost.            

The .NET Framework provides extensive formatting support, which is described in greater detail in the following formatting topics:

The format of the returned string is determined by the NumberFormatInfo object for the current culture. Depending on the format parameter, this object controls symbols such as the negative sign, the group separator, and the decimal point symbol in the output string. To provide formatting information for cultures other than the current culture, call the ToString(String, IFormatProvider) overload.

The following example initializes a BigInteger value and displays it by using each standard format string and some custom format strings.

BigInteger value = BigInteger.Parse("-903145792771643190182");
string[] specifiers = { "C", "D", "D25", "E", "E4", "e8", "F0", 
                        "G", "N0", "P", "R", "X", "0,0.000", 
                        "#,#.00#;(#,#.00#)" };

foreach (string specifier in specifiers)
   Console.WriteLine("{0}: {1}", specifier, value.ToString(specifier));

// The example displays the following output: 
//       C: ($903,145,792,771,643,190,182.00) 
//       D: -903145792771643190182 
//       D25: -0000903145792771643190182 
//       E: -9.031458E+020 
//       E4: -9.0315E+020 
//       e8: -9.03145793e+020 
//       F0: -903145792771643190182 
//       G: -903145792771643190182 
//       N0: -903,145,792,771,643,190,182 
//       P: -90,314,579,277,164,319,018,200.00 % 
//       R: -903145792771643190182 
//       X: CF0A55968BB1A7545A 
//       0,0.000: -903,145,792,771,643,190,182.000 
//       #,#.00#;(#,#.00#): (903,145,792,771,643,190,182.00)            

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4

.NET Framework Client Profile

Supported in: 4

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1

Windows Phone 8.1, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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