C＃Linq .Find（）返回许多结果

Question

I am trying to create a simple search function for my application. I am using Linq's .Find() method to search through a list of objects. It all works very well, the only problem I'm currently having is that I only get the first result. I know for a fact that there are more than one results to be had, but I only get one. Here is my code:

case 5: {
    //Search for Price

    Product searchResult = tempList.Find(x => x.getPrice() == searchPrice);
    if (searchResult != null) {
        //Present Result
        searchTable.Rows.Add(convertIDValue(searchResult.getProductID()), searchResult.getTitle(), searchResult.getYear(), searchResult.getAmount(), searchResult.getPrice());
    }
    else {
        MessageBox.Show("No product with that price", "0 results");
    }

    break;
}

I thought I could change Product searchResult into List<Product> searchResults in order to get a list of Products, then loop through that list. But that gave me an error saying:

Cannot implicitly convert type '.Product' to 'System.Collections.Generic.List<.Product>

Is there any way to get Linq's .Find() to return multiple results?

Answer 1

Use Where() and ToList() to get all objects, matching the condition into a List

replace

Product searchResult = tempList.Find(x => x.getPrice() == searchPrice);

with

List<Product> searchResult = tempList.Where(x => x.getPrice() == searchPrice).ToList();

Answer 2

为此有一个FindAll方法：

List<Product> products = tempList.FindAll(x => x.getPrice() == searchPrice);

Answer 3

Find() searches for an element that matches the conditions defined by the specified predicate, and returns the first occurrence within the entire List.

You need to use FindAll() instead.

Answer 4

Microsoft explains the "Find()" method :"Searches for an element that matches the conditions defined by the specified predicate, and returns the first occurrence within the entire List."

I would suggest you to use this Where() method from Linq extension.

Don't forget to import "using System.Linq" in your current class.

Answer 5

Product searchResult = 

means you are declaring one element. The thing you need is a collection of products, like:

IEnumerable<product> searchResult  =

The easiest way to do it is to change Find() to where():

IEnumerable<product> searchResult = tempList.Where(x => x.getPrice() == searchPrice);

this will create some collection of product's. It will be easier to maintain as a list, so:

list<product> searchResult = tempList.Where(x => x.getPrice() == searchPrice).toList();

Read about IEnumerable interface :)