[API Proposal]: Add Support for ToBase In BigInteger Parsing

[j0nimost]

Background and motivation

Given a string, the current implementation of BigInteger.Parse and BigInteger.TryParse lacks support for ToBase i.e.; 2, 8, 10, 16

API Proposal

// Add Support For String and/or ReadOnlySpan<char>

public static BigInteger Parse(string value, int tobase);
public static BigInteger Parse(ReadOnlySpan<char> value, int tobase);


public static bool TryParse(string value, int tobase, out BigInteger result);
public static bool TryParse(ReadOnlySpan<char> value, int tobase, out BigInteger result);

API Usage

// Given a couple of strings; assumption: large strings
string binary = "101010101100";
string hex = "0x34";

ReadOnlySpan<char> binarySpan = binary.AsSpan();
ReadOnlySpan<char> hexSpan = hex.AsSpan();

BigInteger bigIntA = BigInteger.Parse(binary, 2);
BigInteger bigIntA2 = BigInteger.Parse(binarySpan, 2);

_ = BigInteger.TryParse(hex, 16, out BigInteger bigIntOut)
_ = BigInteger.TryParse(hexSpan, 16, out BigInteger bigIntOut2)

// etc.

Alternative Designs

No response

Risks

No response

[ghost]

Tagging subscribers to this area: @dotnet/area-system-numerics
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Background and motivation

Given a string, the current implementation of BigInteger.Parse and BigInteger.TryParse lacks support for ToBase i.e.; 2, 8, 10, 16

API Proposal

// Add Support For String and/or ReadOnlySpan<char>

public static BigInteger Parse(string value, int tobase);
public static BigInteger Parse(ReadOnlySpan<char> value, int tobase);


public static bool TryParse(string value, int tobase, out BigInteger result);
public static bool TryParse(ReadOnlySpan<char> value, int tobase, out BigInteger result);

API Usage

// Given a couple of strings; assumption: large strings
string binary = "101010101100";
string hex = "0x34";

ReadOnlySpan<char> binarySpan = binary.AsSpan();
ReadOnlySpan<char> hexSpan = hex.AsSpan();

BigInteger bigIntA = BigInteger.Parse(binary, 2);
BigInteger bigIntA2 = BigInteger.Parse(binarySpan, 2);

_ = BigInteger.TryParse(hex, 16, out BigInteger bigIntOut)
_ = BigInteger.TryParse(hexSpan, 16, out BigInteger bigIntOut2)

// etc.

Alternative Designs

No response

Risks

No response

Author:	j0nimost
Assignees:	-
Labels:	api-suggestion, area-System.Numerics, untriaged
Milestone:	-

[j0nimost]

An additional consideration is to add isUnsigned and isBigEndian flags to these methods.

[tannergooding]

Parse APIs explicitly do not take a base parameter. You are expected to call the overloads that take a System.Globalization.NumberStyles instead (such as Parse(string, NumberStyles)) and pass in the relevant styles.

For hexadecimal, this would be NumberStyles.HexNumber.
For binary, this will be NumberStyles.BinaryNumber once we finish implementing #83619

decimal is already supported as the default. There are no current plans for octal, but if there is enough interest in it in the future, it would likely be NumberStyles.OctalNumber