how can I verify the existence of a field item and change its value?

Question

I have to check that the item has the field "In training", if that field exists and is different from 1, I have to set it to 1.

var field = "In Allenamento";
        var value = "0";
        var edited = (field = "1");

       if (field != null && field == value)
        {
            field = "1";

        }

            using (new Sitecore.SecurityModel.SecurityDisabler())
            {
                item.Editing.BeginEdit();
                item.Fields[field].Value = field;
                item.Editing.EndEdit();
                log.AppendLine(item.ID + "edited");
            }
       
    }

I am aware that I have written nonsense, so I ask for support

Answer 1

1. Take the field by its name ("In Allenamento" or "In Training")
2. If field is null it means that it does not exist on that item
3. Check if its value is not "1"
4. Start editing
5. Update value
6. End editing

using (new Sitecore.SecurityModel.SecurityDisabler())
{
    var inTrainingField = item.Fields["In Allenamento"];
    if (inTrainingField != null && inTrainingField.Value != "1")
    {
        item.Editing.BeginEdit();
        item.Fields["In Allenamento"].Value = "1";
        item.Editing.EndEdit();
        log.AppendLine(item.ID + "edited");
    }
}