比较两个字符串并获得差异

Question

How can i compare two strings in c# and gets the difference?

for example:

String1 : i have a car

string2 : i have a new car bmw

result: new, bmw

Answer 1

You need to make sure the larger set is on the left hand side of the Except (not sure if there is a pure Linq way to achieve that):

    static void Main(string[] args)
    {
        string s1 = "i have a car a car";
        string s2 = "i have a new car bmw";

        List<string> diff;
        IEnumerable<string> set1 = s1.Split(' ').Distinct();
        IEnumerable<string> set2 = s2.Split(' ').Distinct();

        if (set2.Count() > set1.Count())
        {
            diff = set2.Except(set1).ToList();
        }
        else
        {
            diff = set1.Except(set2).ToList();
        }
    }

Answer 2

Based off your question (It is a bit vague.) this should work.

var first = string1.Split(' ');
var second = string2.Split(' ');
var primary = first.Length > second.Length ? first : second;
var secondary = primary == second ? first : second;
var difference = primary.Except(secondary).ToArray();

At the top of your file make sure you include:

using System.Linq;

Answer 3

You can use a difference algorithm for this task. The paper " An O(ND) Difference Algorithm and Its Variations " describes a quite powerful algorithm to accomplish this task. For an implementation in C#, you can have a look at " An O(ND) Difference Algorithm for C# ", but IMHO it surely is more interesting to have a look at the paper and implement it for yourself in case you're interested on how the algorithm works in detail.