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patterncsharpMinor

Setting enum flags by string (in any order)

Submitted by: @import:stackexchange-codereview··
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orderenumanysettingflagsstring

Problem

I want to set flags which are given in string representation in any order. And it is intimidating, because you have to check like 2^3 possible options in my occassion. I was just wondering is there any better way to do that than just simple brute-force. Any optimization and readability improvment would be great. This is my code:

[Flags]
public enum salaryFeatures
{
Children = 1,
Graduate = 2,
Disability = 4
}

class Program
{

public static void Main()
{
    string Employee = "10023 Mark Male 6.7 70 30 20 Children Graduate";
    salaryFeatures f;
    f = GetFeaturesByString(Employee);
}

public static salaryFeatures GetFeaturesByString(string fields)
{
    bool children = false;
    bool graduate = false;
    bool disability = false;
    salaryFeatures features = new salaryFeatures();

    if (fields.ToLower().Contains("children")) children = true;
    if (fields.ToLower().Contains("graduate")) graduate = true;
    if (fields.ToLower().Contains("disability")) disability = true;

    if (children && graduate && disability)
    {
        return features = salaryFeatures.Children | salaryFeatures.Disability | salaryFeatures.Graduate;
    }
    if (children && graduate)
    {
        return features = salaryFeatures.Children | salaryFeatures.Graduate;
    }
    if (children && disability)
    {
        return features = salaryFeatures.Children | salaryFeatures.Disability;
    }
    if (children)
    {
        return features = salaryFeatures.Children;
    }
    if (graduate && disability)
    {
        return features = salaryFeatures.Graduate | salaryFeatures.Disability;
    }
    if (graduate)
    {
        return features = salaryFeatures.Graduate;
    }
    if (disability)
    {
        return features = salaryFeatures.Disability;
    }
    return features;
}
}

Solution

Here is my take on your code

[Flags]
public enum SalaryFeatures
{
  None= 0,
  Children = 1,
  Graduate = 2,
  Disability = 4
}

class Program
{

  public static void Main()
  {
    string Employee = "10023 Mark Male 6.7 70 30 20 Children Graduate";
    SalaryFeatures f;
    f = GetFeaturesByString(Employee);
    // f.Dump(); //LinqPad only
  }

  public static SalaryFeatures GetFeaturesByString(string fields)
  {
    SalaryFeatures features = SalaryFeatures.None;

    if (fields.IndexOf("children", StringComparison.OrdinalIgnoreCase) >= 0) features |= SalaryFeatures.Children;
    if (fields.IndexOf("graduate", StringComparison.OrdinalIgnoreCase) >= 0) features |= SalaryFeatures.Graduate;
    if (fields.IndexOf("disability", StringComparison.OrdinalIgnoreCase) >= 0) features |= SalaryFeatures.Disability;

    return features;
  }
}


First of the definition of your Enumeration is not complete. You need to define a None value for it


Use None as the name of the flag enumerated constant whose value is
zero. You cannot use the None enumerated constant in a bitwise AND
operation to test for a flag because the result is always zero.
However, you can perform a logical, not a bitwise, comparison between
the numeric value and the None enumerated constant to determine
whether any bits in the numeric value are set.

See also the Guidelines when defining a Flags enum. I also change the naming of the enum to PascalCase (SalaryFeatures).

After that I have improved your method GetFeaturesByString to use bitwise OR to combine the values depending on the values that are found in your string. I also use the method IndexOf(string, StringComparison) to check if the search string exists in the source string, instead of using ToLower() and Contains().

Code Snippets

[Flags]
public enum SalaryFeatures
{
  None= 0,
  Children = 1,
  Graduate = 2,
  Disability = 4
}

class Program
{

  public static void Main()
  {
    string Employee = "10023 Mark Male 6.7 70 30 20 Children Graduate";
    SalaryFeatures f;
    f = GetFeaturesByString(Employee);
    // f.Dump(); //LinqPad only
  }

  public static SalaryFeatures GetFeaturesByString(string fields)
  {
    SalaryFeatures features = SalaryFeatures.None;

    if (fields.IndexOf("children", StringComparison.OrdinalIgnoreCase) >= 0) features |= SalaryFeatures.Children;
    if (fields.IndexOf("graduate", StringComparison.OrdinalIgnoreCase) >= 0) features |= SalaryFeatures.Graduate;
    if (fields.IndexOf("disability", StringComparison.OrdinalIgnoreCase) >= 0) features |= SalaryFeatures.Disability;

    return features;
  }
}

Context

StackExchange Code Review Q#144738, answer score: 3

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