String to enum conversion in C#

I have a combo box where I am displaying some entries like:

Equals
Not Equals 
Less Than
Greater Than

Notice that these strings contain spaces. I have a enum defined which matches to these entries like:

enum Operation{Equals, Not_Equals, Less_Than, Greater_Than};

Since space is not allowed, I have used _ character.

Now, is there any way to convert given string automatically to an enum element without writing a loop or a set of if conditions my self in C#?

I suggest building a Dictionary<string, Operation> to map friendly names to enum constants and use normal naming conventions in the elements themselves.

enum Operation{ Equals, NotEquals, LessThan, GreaterThan };

var dict = new Dictionary<string, Operation> {
    { "Equals", Operation.Equals },
    { "Not Equals", Operation.NotEquals },
    { "Less Than", Operation.LessThan },
    { "Greater Than", Operation.GreaterThan }
};

var op = dict[str];

Alternatively, if you want to stick to your current method, you can do (which I recommend against doing):

var op = (Operation)Enum.Parse(typeof(Operation), str.Replace(' ', '_'));

Operation enumVal = (Operation)Enum.Parse(typeof(Operation), "Equals")

For "Not Equals", you obv need to replace spaces with underscores in the above statement

EDIT: The following version replaces the spaces with underscores before attempting the parsing:

string someInputText;
var operation = (Operation)Enum.Parse(typeof(Operation), someInputText.Replace(" ", "_"));

Either create a dedicated mapper using a dictionary (per Mehrdad's answer) or implement a TypeConverter.

Your custom TypeConverter could either replace " " -> "_" (and vice versa) or it could reflect the enumeration and use an attribute for determining the display text of the item.

enum Operation
{
    [DisplayName("Equals")]
    Equals, 

    [DisplayName("Not Equals")]
    Not_Equals, 

    [DisplayName("Less Than")]
    Less_Than, 

    [DisplayName("Greater Than")]
    Greater_Than
};

public class OperationTypeConverter : TypeConverter
{
    private static Dictionary<string, Operation> operationMap;

    static OperationTypeConverter()
    {
        BindingFlags bindingFlags = BindingFlags.Static | BindingFlags.GetField
            | BindingFlags.Public;

        operationMap = enumType.GetFields(bindingFlags).ToDictionary(
            c => GetDisplayName(c)
            );
    }

    private static string GetDisplayName(FieldInfo field, Type enumType)
    {
        DisplayNameAttribute attr = (DisplayNameAttribute)Attribute.GetCustomAttribute(typeof(DisplayNameAttribute));

        return (attr != null) ? attr.DisplayName : field.Name;
    }

    public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
    {
        string stringValue = value as string;

        if (stringValue != null)
        {
            Operation operation;
            if (operationMap.TryGetValue(stringValue, out operation))
            {
                return operation;
            }
            else
            {
                throw new ArgumentException("Cannot convert '" + stringValue + "' to Operation");
            }
        }
    }
}

This implementation could be improved in several ways:

Make it generic
Implement ConvertTo
Support FlagsAttribute

You can use the Parse method:

 Operarion operation = (Operation)Enum.Parse(typeof(Operation), "Not_Equals");

Some examples here

String to enum conversion in C#

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