dotnet/runtime

StringBuilder Has Different Equals Implementations

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#41,230 opened on Aug 23, 2020

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area-System.Runtimedocumentationhelp wanted

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Description

Description

StringBuilder has two different versions of Equals. Equals(object) uses the version defined in class Object, while Equals(StringBuilder) uses the in-class implementation. These two different behaviors are confusing.

Considering these code. The different results are confusing.

StringBuilder a = new StringBuilder();
StringBuilder b = new StringBuilder();
object c = b;
a.Append("abc");
b.Append("abc");
Console.WriteLine(a.Equals(b)); // True
Console.WriteLine(a.Equals(c)); // False

Configuration

OS Name: Windows OS Version: 10.0.18363 OS Platform: Windows RID: win10-x64 Base Path: C:\Program Files\dotnet\sdk\3.1.301\

.NET Core SDK: Version: 3.1.301 Commit: 7feb845744

Regression?

Not noticed.

Other information

None.

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