藍色、天空、貓: 【C# 語言】三種尋找 List 中資料的方法 ForEach、FindAll、Linq Where Select

居裡貓最近跟人討論到幾個尋找List中尋找特定資料的方法，所以順便做了這個練習。

接下來就讓我們看看到底這幾種方法怎麼使用囉！

在很多時候我們會有一些資料，它會有自己特有的內容以及規則，

有一些時候需要去尋找資料集中特定的資料內容，

但是資料一旦很多的時候，通常都是使用迴圈來一筆一筆確認，

在某些時候迴圈是很好用的東西，但寫作上不那麼便利跟迅速，

剛好這些條件的設計下，有除了迴圈以外的方法。

今天要介紹練習的就是這三種方法：

For Each

List.FindAll

Linq - Where Select

這三種方法的後面兩種，就是一種寫作方式便利快速的作法，

但是處理的結果也跟常用的迴圈相同。

今天居裡貓設計了一個資料格式類別，包含 No, Name, Score 的資料格式。

public class DataClass
{
public int No { get; set; }
public string Name { get; set; }
public int Score { get; set; }
public DataClass(int _no, string _name, int _score)
{
No = _no;
Name = _name;
Score = _score;
}
}

根據這樣的資料格式，來尋找特定的成績大於某數的結果，

利用上面提到的三個方法來尋找這樣的結果。

接著就來說明一下這個練習的程式設計樣式：

介面中包含幾個元件，說明如下：

Reset Data : 根據後方 NumericUpDown 裡面的數值初始化上述說明的資料格式。

For Each : 利用 For Each 的方法，尋找成績大於 Find Score 後方 NumericUpDown 數值的數。

Find All : 利用 List.FindAll 的方法，尋找成績大於 Find Score 後面 NumericUpDown 數值的數。

Linq Select : 利用 Linq 中 Where 和 Select 的方法，尋找成績大於 Find Score 後面 NumericUpDown 數值的數。

Original Data : 是這次資料的總資料內容。

Find Data : 是尋找成功的資料內容。

介紹完介面之後，讓我們來看一下尋找的結果吧！

橘色框線內為 For Each 的搜尋結果，花費時間跟尋找的筆數。

綠色框線內為 Find All 的搜尋結果，花費時間跟尋找的筆數。

紫色框線內為 Linq Select 的搜尋結果，花費時間跟尋找的筆數。

針對花費的時間來看，便利的寫法並不一定會得到更好的時間花費，

在相同搜尋結果下，如果在需要更快速的處理速度，更少的花費時間，

For Each 的作法不見得不好，

但不要求快速的處理始間下，另外兩種方法的便利寫法、較簡單的程式碼，

或許會讓閱讀的狀態更為良好。

接下來就來看看程式碼吧！

本次範例的介面設計皆由程式碼產生，

所以以下程式碼中會看到介面設計的方法內容，請見諒。

-------------------------------程式碼分割線------------------------------------------------------------

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Diagnostics;
namespace TestFindListData
{
public partial class MainForm : Form
{
#region Fields
private Button _btnUITest;
private Button[] _btnFunction;
private Label[] _lblFunctionCost;
private NumericUpDown[] _nudDataNumber;
private ListBox[] _lsbDataInfo;
private List<DataClass> _lsData;
private List<DataClass> _lsFindScore;
private Random _rndScore;
private Stopwatch _sw;
#endregion // Fields
#region Construct
public MainForm()
{
InitializeComponent();
Initial();
}
#endregion // Construct
#region Event
private void btnUITest_Click(object sender, EventArgs e)
{
this.Controls.Clear();
Initial();
}
private void btnFunction_Click(object sender, EventArgs e)
{
Button _tmpBtn = (Button)sender;
switch (_tmpBtn.Name)
{
case "btnFunctionData":
InitialTestData(Convert.ToInt32(_nudDataNumber.First(x=>x.Name == "nudDataCount").Value));
break;
case "btnFunctionFor":
FunctionForEach(_lsData, Convert.ToInt32(_nudDataNumber.First(x => x.Name == "nudScore").Value));
break;
case "btnFunctionFind":
FunctionFindAll(_lsData, Convert.ToInt32(_nudDataNumber.First(x => x.Name == "nudScore").Value));
break;
case "btnFunctionLinq":
FunctionLinq(_lsData, Convert.ToInt32(_nudDataNumber.First(x => x.Name == "nudScore").Value));
break;
}
}
#endregion // Event
#region Function
#region Private Function
private void Initial()
{
this.Width = 640;
this.Height = 640;
// CreateButtonWithUI(); // This function will create UI reset function
CreateButtonWithFunction(4);
CreateLabelWithFunctionCost(6);
CreateNumbericUpDown(2);
CreateListbox(2);
InitialTestData(10);
}
private void InitialTestData(int _total)
{
if (_lsData == null)
{
_lsData = new List<DataClass>();
}
if (_lsData.Count > 0)
{
_lsData.Clear();
_lsData = new List<DataClass>();
}
_rndScore = new Random();
for (int i = 0; i<_total;i++)
{
_lsData.Add(new DataClass(i, Convert.ToString((char)(i+65)), _rndScore.Next(0, 100)));
}
if (_lsbDataInfo.First(x => x.Name == "lsbOriginalData").Items.Count > 0) { _lsbDataInfo.First(x => x.Name == "lsbOriginalData").Items.Clear(); }
foreach (var tmp in _lsData)
{
_lsbDataInfo.First(x => x.Name == "lsbOriginalData").Items.Add("No: " + tmp.No.ToString() + " Name: " + tmp.Name + " Score: " + tmp.Score);
}
}
private void FunctionForEach(List<DataClass> _ls, int _findScore)
{
if (_ls == null) { MessageBox.Show("The data list is null so will return FunctionForEach"); return; }
_lsFindScore = new List<DataClass>();
_sw = new Stopwatch();
_sw.Reset();
_sw.Start();
foreach(var tmp in _ls)
{
if (tmp.Score > _findScore)
{
_lsFindScore.Add(tmp);
}
}
_sw.Stop();
_lblFunctionCost.First(x => x.Name == "lblFunctionCostFor").Text = "For Cost: " + _sw.Elapsed.TotalMilliseconds.ToString() + " ms Find count: " + _lsFindScore.Count.ToString();
if (_lsbDataInfo.First(x => x.Name == "lsbFindData").Items.Count > 0) { _lsbDataInfo.First(x => x.Name == "lsbFindData").Items.Clear(); }
foreach (var tmp in _lsFindScore)
{
_lsbDataInfo.First(x => x.Name == "lsbFindData").Items.Add("No: " + tmp.No.ToString() + " Name: " + tmp.Name + " Score: " + tmp.Score);
}
}
private void FunctionFindAll(List<DataClass> _ls, int _findScore)
{
if (_ls == null) { MessageBox.Show("The data list is null so will return FunctionForEach"); return; }
_lsFindScore = new List<DataClass>();
_sw = new Stopwatch();
_sw.Reset();
_sw.Start();
_lsFindScore = _lsData.FindAll(x => x.Score > _findScore).ToList();
_sw.Stop();
_lblFunctionCost.First(x => x.Name == "lblFunctionCostFind").Text = "FindAll Cost: " + _sw.Elapsed.TotalMilliseconds.ToString() + " ms Find count: " + _lsFindScore.Count.ToString();
if (_lsbDataInfo.First(x => x.Name == "lsbFindData").Items.Count > 0) { _lsbDataInfo.First(x => x.Name == "lsbFindData").Items.Clear(); }
foreach (var tmp in _lsFindScore)
{
_lsbDataInfo.First(x => x.Name == "lsbFindData").Items.Add("No: " + tmp.No.ToString() + " Name: " + tmp.Name + " Score: " + tmp.Score);
}
}
private void FunctionLinq(List<DataClass> _ls, int _findScore)
{
if (_ls == null) { MessageBox.Show("The data list is null so will return FunctionForEach"); return; }
_lsFindScore = new List<DataClass>();
_sw = new Stopwatch();
_sw.Reset();
_sw.Start();
_lsFindScore =
(from tmp in _lsData
where tmp.Score > _findScore
select tmp).ToList();
_sw.Stop();
_lblFunctionCost.First(x => x.Name == "lblFunctionCostLinq").Text = "LinqSelect Cost: " + _sw.Elapsed.TotalMilliseconds.ToString() + " ms Find count: " + _lsFindScore.Count.ToString();
if (_lsbDataInfo.First(x => x.Name == "lsbFindData").Items.Count > 0) { _lsbDataInfo.First(x => x.Name == "lsbFindData").Items.Clear(); }
foreach (var tmp in _lsFindScore)
{
_lsbDataInfo.First(x => x.Name == "lsbFindData").Items.Add("No: " + tmp.No.ToString() + " Name: " + tmp.Name + " Score: " + tmp.Score);
}
}
#region Create UI
private void CreateButtonWithUI()
{
_btnUITest = new Button();
_btnUITest.Name = "btnUITest";
_btnUITest.Text = "UI Test";
_btnUITest.Location = new Point(this.Width - 100, this.Height - 100);
_btnUITest.Click += btnUITest_Click;
this.Controls.Add(_btnUITest);
}
private void CreateButtonWithFunction(int _total)
{
_btnFunction = new Button[_total];
for (int i = 0; i<_total;i++)
{
_btnFunction[i] = new Button();
switch(i)
{
case 0:
_btnFunction[i].Name = "btnFunctionData";
_btnFunction[i].Text = "Reset Data";
_btnFunction[i].Size = new Size(100, 20);
_btnFunction[i].Location = new Point(20, 20);
_btnFunction[i].Click += btnFunction_Click;
break;
case 1:
_btnFunction[i].Name = "btnFunctionFor";
_btnFunction[i].Text = "For Each";
_btnFunction[i].Size = new Size(100, 20);
_btnFunction[i].Location = new Point(20, 50);
_btnFunction[i].Click += btnFunction_Click;
break;
case 2:
_btnFunction[i].Name = "btnFunctionFind";
_btnFunction[i].Text = "Find All";
_btnFunction[i].Size = new Size(100, 20);
_btnFunction[i].Location = new Point(20, 80);
_btnFunction[i].Click += btnFunction_Click;
break;
case 3:
_btnFunction[i].Name = "btnFunctionLinq";
_btnFunction[i].Text = "Linq Select";
_btnFunction[i].Size = new Size(100, 20);
_btnFunction[i].Location = new Point(20, 110);
_btnFunction[i].Click += btnFunction_Click;
break;
}
this.Controls.Add(_btnFunction[i]);
}
}
private void CreateLabelWithFunctionCost(int _total)
{
_lblFunctionCost = new Label[_total];
for (int i = 0; i<_total;i++)
{
_lblFunctionCost[i] = new Label();
switch(i)
{
case 0:
_lblFunctionCost[i].Name = "lblFunctionCostFor";
_lblFunctionCost[i].Text = "For Cost: ";
_lblFunctionCost[i].Location = new Point(140, 50);
_lblFunctionCost[i].Size = new Size(300, 20);
break;
case 1:
_lblFunctionCost[i].Name = "lblFunctionCostFind";
_lblFunctionCost[i].Text = "FindAll Cost: ";
_lblFunctionCost[i].Location = new Point(140, 80);
_lblFunctionCost[i].Size = new Size(300, 20);
break;
case 2:
_lblFunctionCost[i].Name = "lblFunctionCostLinq";
_lblFunctionCost[i].Text = "LinqSelect Cost: ";
_lblFunctionCost[i].Location = new Point(140, 110);
_lblFunctionCost[i].Size = new Size(300, 20);
break;
case 3:
_lblFunctionCost[i].Name = "lblOriginalData";
_lblFunctionCost[i].Text = "Original Data: ";
_lblFunctionCost[i].Location = new Point(20, 140);
_lblFunctionCost[i].Size = new Size(200, 20);
break;
case 4:
_lblFunctionCost[i].Name = "lblFindData";
_lblFunctionCost[i].Text = "Find Data: ";
_lblFunctionCost[i].Location = new Point(310, 140);
_lblFunctionCost[i].Size = new Size(200, 20);
break;
case 5:
_lblFunctionCost[i].Name = "lblScore";
_lblFunctionCost[i].Text = "Find Score: ";
_lblFunctionCost[i].Location = new Point(310, 20);
_lblFunctionCost[i].Size = new Size(100, 20);
break;
}
this.Controls.Add(_lblFunctionCost[i]);
}
}
private void CreateNumbericUpDown(int _total)
{
_nudDataNumber = new NumericUpDown[_total];
for (int i = 0;i<_total;i++)
{
_nudDataNumber[i] = new NumericUpDown();
switch (i)
{
case 0:
_nudDataNumber[i].Name = "nudDataCount";
_nudDataNumber[i].Value = 10;
_nudDataNumber[i].Size = new Size(50, 20);
_nudDataNumber[i].Location = new Point(140, 20);
_nudDataNumber[i].Minimum = 0;
_nudDataNumber[i].Maximum = 9999;
_nudDataNumber[i].Increment = 1;
break;
case 1:
_nudDataNumber[i].Name = "nudScore";
_nudDataNumber[i].Value = 10;
_nudDataNumber[i].Size = new Size(50, 20);
_nudDataNumber[i].Location = new Point(410, 20);
_nudDataNumber[i].Minimum = 0;
_nudDataNumber[i].Maximum = 100;
_nudDataNumber[i].Increment = 1;
break;
}
this.Controls.Add(_nudDataNumber[i]);
}
}
private void CreateListbox(int _total)
{
_lsbDataInfo = new ListBox[_total];
for (int i = 0; i<_total;i++)
{
_lsbDataInfo[i] = new ListBox();
switch(i)
{
case 0:
_lsbDataInfo[i].Name = "lsbOriginalData";
_lsbDataInfo[i].Location = new Point(20, 160);
_lsbDataInfo[i].Size = new Size(250, 400);
break;
case 1:
_lsbDataInfo[i].Name = "lsbFindData";
_lsbDataInfo[i].Location = new Point(310, 160);
_lsbDataInfo[i].Size = new Size(250, 400);
break;
}
this.Controls.Add(_lsbDataInfo[i]);
}
}
#endregion // Create UI
#endregion Private Function
#endregion // Function
}
public class DataClass
{
public int No { get; set; }
public string Name { get; set; }
public int Score { get; set; }
public DataClass(int _no, string _name, int _score)
{
No = _no;
Name = _name;
Score = _score;
}
}
}

藍色、天空、貓

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2021年1月31日星期日

【C# 語言】三種尋找 List 中資料的方法 ForEach、FindAll、Linq Where Select

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