Cause

A call toBitConverter.ToString followed by a call toString.Replace to remove dashes is used to encode bytes to a hexadecimal string representation.This rule also fires ifString.ToLower is used in the call chain.

Rule description

UseConvert.ToHexString orConvert.ToHexStringLower when encoding bytes to a hexadecimal string representation. These methods are more efficient and allocation-friendly than usingBitConverter.ToString in combination withString.Replace to remove dashes andString.ToLower.

How to fix violations

To fix a violation of this rule, replace the call chain with eitherConvert.ToHexString orConvert.ToHexStringLower.

Example

The following code snippet shows a violation of CA1872:

using System;using System.Text;class HelloWorldEncoder{    private readonly byte[] _data = Encoding.ASCII.GetBytes("Hello World");    public string Encode()    {        return BitConverter.ToString(_data).Replace("-", "");    }    public string EncodeToLower()    {        return BitConverter.ToString(_data).Replace("-", "").ToLower();    }}

Imports SystemImports System.TextClass HelloWorldEncoder    Private ReadOnly _data As Byte() = Encoding.ASCII.GetBytes("Hello World")    Public Function Encode() As String        Return BitConverter.ToString(_data).Replace("-", "")    End Function    Public Function EncodeToLower() As String        Return BitConverter.ToString(_data).Replace("-", "").ToLower()    End FunctionEnd Class

The following code snippet fixes the violation:

using System;using System.Text;class HelloWorldEncoder{    private readonly byte[] _data = Encoding.ASCII.GetBytes("Hello World");    public string Encode()    {        return Convert.ToHexString(_data);    }    public string EncodeToLower()    {        return Convert.ToHexStringLower(_data);    }}

Imports SystemImports System.TextClass HelloWorldEncoder    Private ReadOnly _data As Byte() = Encoding.ASCII.GetBytes("Hello World")    Public Function Encode() As String        Return Convert.ToHexString(_data)    End Function    Public Function EncodeToLower() As String        Return Convert.ToHexStringLower(_data)    End FunctionEnd Class

When to suppress warnings

It is safe to suppress a warning from this rule; however, we recommend that you use eitherConvert.ToHexString orConvert.ToHexStringLower.

Suppress a warning

If you just want to suppress a single violation, add preprocessor directives to your source file to disable and then re-enable the rule.

#pragma warning disable CA1872// The code that's violating the rule is on this line.#pragma warning restore CA1872

To disable the rule for a file, folder, or project, set its severity tonone in theconfiguration file.

[*.{cs,vb}]dotnet_diagnostic.CA1872.severity = none

For more information, seeHow to suppress code analysis warnings.