Generic math - Factorial method

Here is a example of a generic math factorial method in C# 11. Generic math allows you to make numeric methods that makes use of the INumber generic interface, which got many static virtual methods where you can make a numeric method that supports different kinds of number types, such as decimal, int, float and double. The code below calculates the factorial of some values in an array. We have inserted a double value here that shows that Factorial of a double or any number with decimal works a bit different than ints, as the decimal part takes part here. The factorial of 0! is defined as 1 and we multiply n with n-1 as long as n > 0. Note the use of T.One and T.Zero here, defined as
static virtual members of the different number types in C#.

void Main()
{
	var someNums = new[] { 1, 2, 3, 3.141592, 5};
	var fact = someNums.Select(n =>  Factorial(n));
	fact.Dump();
	
}

T Factorial<T>(T num)
where T : INumber<T>
{
	var result = T.One;
	while (num > T.Zero){
		result *= num;
		num--;
	}
	return result;
}

Output shows the result in Linqpad 7 after having specified using .NET 7:

Trøndersk dialekttemp with C# 11 og and patterns

This article demonstrates the use of relational patterns in C# 11. First off, relational patterns allow us to test how a given value /variable compares to constants. If we want to have multiple conditions we can use and operator not shown here. I have here different conditions / intervals for temperaturs outputting the temperature and description of the weather in some local language of mine from Norway (Trøndersk / Trondheim city).

	   
    
foreach (var iteration in Enumerable.Range(0, 20)){
    var tæmpen = new Random().Next(-60, 60);
    
    var været = $"Været e i dag {tæmpen}C og på Trondheimsdialækt: {tæmpen switch 
    {
        <= -50 => "Du træng eitt nytt termometer. For kaldt!",
        <= -35 => "Småfuggel'n dætt dau fra trær'n",
        <= -30 => "Båinnspeika",
        <= -25 => "Få inn katta!",
        <= -20 => "Gnallerfrost",
        <= -10 => "Kjøle kaaalt",
        <= -5  => "Kaillvoli",
        <= 5 => "Kaillhustri",
        <= 10 => "Julivær",
        <= 15 => "Godværsle",
        <= 20 => "Kjøle varmt",
        <= 25 => "Råådeili",
        <= 30 => "Steikvarmt",
        <= 40 => "Søkke heitt",
        <= 50 => "Kokheitt",
        _ => "Du træng eitt nytt termometer. For varmt!"
    }}";
    
    System.Console.WriteLine(været);
} 
    
    

As we can see, in C# 11, we can do a lot more inside string interpolation expressions and now allow multiple lines, including relational patterns. It can be quite handy to use, when .NET 7 and C# 11 reaches mainstream usage. The text here is based upon a dialect based thermometer, available for purchase from here: https://dialekttempen.no/butikk/termometer/fylker/sor-trondelag/trondheim-munkholmen/#&gid=1&pid=1

Running eclint locally in development environment

If you have come accross eclint in Azure Devops or in other scenarios, you might want to run this in local development instead to get your linting return an error, possible crashing the build pipeline in Azure Devops. Eclints checks the .editorconfig file of your VS solution and reports if your code is badly formatted according to this file code style rules. Here is a typical eclint setup written with YAML

 
 # Runs ECLINT CHECK. This verfies that code conforms to editor config file.
parameters:
  lintingResultArtifactName: 'LINTING' # Name of published artifact with results.

steps:
- task: Bash@3
  displayName: 'Template steps-linting'
  inputs:
    targetType: 'inline'
    script: 'echo Template steps linting'
- task: Bash@3
  displayName: 'Install ECLINT'
  inputs:
    targetType: 'inline'
    script: |
        sudo npm install -g eclint
    failOnStderr: false
- task: Bash@3
  displayName: 'ECLINT check'
  inputs:
    targetType: 'inline'
    script: |
      eclint check $(git ls-files -- . ':!:*.sln' . ':!:*.sln.DotSettings') > $(Build.ArtifactStagingDirectory)/eclint.txt 2>&1
      file=$(Build.ArtifactStagingDirectory)/eclint.txt
      if [ -s "$file" ]
      then
        echo " ECLint reported errors - build failed 😔" 1>&2
        cat $file
        exit 1
      else
        echo " No errors found. You did good 👍 "
        exit 0
      fi
    failOnStderr: false
- task: PublishBuildArtifacts@1
  displayName: 'Publish artifact'
  condition: succeededOrFailed()
  inputs:
    PathtoPublish: '$(Build.ArtifactStagingDirectory)'
    ArtifactName: ${{ parameters.lintingResultArtifactName }}
    publishLocation: 'Container'


 

The following shell script can be run with Git Bash in for example Windows environments to run eclint locally.

 
 #!/bin/bash

GREEN='\033[0;32m'
RED='\033[0;31m'
NC='\033[0m' # No Color

exists() {
    command -v "$1" > /dev/null 2>&1
}

runEcLint(){
    echo -e "Starting up eclint linting the files of the solution! ${GREEN}[SUCCESS]${NC} Current folder:"
    pwd
    eclint check $(git ls-files -- . ':!:*.sln' . ':!:*.sln.DotSettings') > eclint.txt 2>&1
    file=eclint.txt
    if [ -s "$file" ]
    then
        echo " ECLint reported errors - build failed 😔" 1>&2
        cat $file
        echo -e "ECLint command reported a ${RED}[FAIL]${NC}. Correct the errors."
        rm eclint.txt
        exit 1
    else
        echo " No errors found. You did good 👍 "
        echo -e "ECLint command reported a ${GREEN}][SUCCESS]${NC}"
        rm eclint.txt
        exit 0
    fi
}

echo "Running eclint locally to check the solution. Checking LOCALDEV environment.."

echo "Checking that npm is installed globally.. "
if  ! [[ "exists npm" ]]; then
    echo -e "Npm is not installed globally. ${RED} [FAIL]${NC}"
    echo "Install npm globally first before running this script! See: https://nodejs.org/en/download/"
    echo "Recommended next step: Install LTS of jnodejs together with npm"
    exit 1
else
    echo -e "You have already installed npm (globally). ${GREEN} [SUCCESS]${NC}"
fi

echo "Checking that eclint is installed globally.. "
if  !  [[ "exists eclint" ]]; then
    echo -e "eclint is not installed globally. ${RED} [FAIL]${NC}"
    echo "Make sure you run this script with sufficient access : Attempting to install eclint globally next."
    echo "Trying to run this command to install eclint: npm install eclint -g"
    npm install -g eclint
    echo -e "\neclint should now be installed. Continuing! ${GREEN} [SUCCESS]${NC}"
else
    echo -e "You have already installed eclint (globally). ${GREEN} [SUCCESS]${NC}"
fi

echo "Switching up a folder to run at root folder of the source.."
pushd ..
echo -e "Switched to parent folder ${GREEN}[SUCCESS]${NC}"

runEcLint

popd #back to the eclint folder
  
 

In case you are running WSL, chances are that you must check if a command is available like this: if ! [ -x "$(command -v npm)" ]; then Also, you might need to add 'sudo' before the npm install -g command. The following launch.json file shows how you can debug inside VsCode Bash scripts, using extension Bash Debug for VsCode.

 
 {
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "type": "bashdb",
            "request": "launch",
            "name": "Bash-Debug",
            "cwd": "${workspaceFolder}",
            "program": "${file}",
            "args": []
            }
    ]
}
 

I tested the script against a solution at work and it spotted the intended eclint warnings for multiple files, as a proof of concept. This makes it easier to fix up eclint errors before pushing them to Azure Devops !