从C＃中的文本文件中读取
我有以下程序将（输出）信息发送到文本文件，但现在我想从文本文件中读取（输入）。 任何建议将不胜感激。 我已经评论了一些“我认为”我需要做的事情; 但我不确定如何继续。
using System.Windows.Forms; using System.IO; namespace Input_Output { public partial class Grades : Form { private StreamWriter output; private StreamReader input; public Grades() { InitializeComponent(); } private void label4_Click(object sender, EventArgs e) { } private void btnCreate_Click(object sender, EventArgs e) { btnEnter.Visible = true; btnClose.Visible = true; txtFirst.Visible = true; txtLast.Visible = true; lblFirst.Visible = true; lblLast.Visible = true; listBox1.Visible = true; lblStatus.Visible = true; lblGrade.Visible = true; lblCourse.Visible = true; cmbID.Visible = true; lblID.Visible = true; txtCourse.Visible = true; txtGrade.Visible = true; lblStatus.Visible = true; DialogResult result; string fileName; using (SaveFileDialog chooser = new SaveFileDialog()) { result = chooser.ShowDialog(); fileName = chooser.FileName; } output = new StreamWriter(fileName); btnCreate.Enabled = false; txtFirst.Visible = true; txtLast.Visible = true; lblFirst.Visible = true; lblLast.Visible = true; btnEnter.Visible = true; btnClose.Visible = true; } private void btnClose_Click(object sender, EventArgs e) { //Close button pushes information from the listbox in to the text file output.Close(); lblStatus.ForeColor = Color.Red; lblStatus.Text = "Output File"; btnCreate.Enabled = true; listBox1.Items.Clear(); cmbID.Text = ""; } private void btnEnter_Click(object sender, EventArgs e) { // Enter button sends information to the list box, a Message Box prompts user to check for accuracy. //Close button pushes information to the Text file. string last = ""; string first = ""; string course = ""; string grade = ""; if (txtFirst.Text != "" && txtLast.Text != "" && txtCourse.Text != "") { last = txtFirst.Text; first = txtLast.Text; course = txtCourse.Text; grade = txtGrade.Text; output.WriteLine (last + "\t"+ "\t" + first + ":"+ "\t" + cmbID.SelectedItem + "_" + course + "_" + grade ); listBox1.Items.Add(txtLast.Text + "," + txtFirst.Text + ":" + cmbID.SelectedItem + "-" + txtCourse.Text + "-" + txtGrade.Text); lblStatus.ForeColor = Color.Navy; lblStatus.Text = "Entry Saved"; txtFirst.Text = ""; txtLast.Text = ""; txtCourse.Text = ""; txtGrade.Text = ""; txtFirst.Focus(); } else { lblStatus.ForeColor = Color.Red; lblStatus.Text = "Empty text box or boxes"; } MessageBox.Show("Please verify that the information is correct before proceeding"); } private void btnExit_Click(object sender, EventArgs e) { Application.Exit(); } private void Grades_Load(object sender, EventArgs e) { } private void button1_Click(object sender, EventArgs e) { DialogResult result; string fileName; using (OpenFileDialog chooser = new OpenFileDialog()) { result = chooser.ShowDialog(); fileName = chooser.FileName; } //while loop? //if variable is null, it's the end of the record //variable= !null //txt read int variable TxtFile.Text += Rec + "\r\n"; while rec !=null; } } } 要一次读取一行文本文件，您可以这样做：
using System.IO; using (var reader = new StreamReader(fileName)) { string line; while ((line = reader.ReadLine()) != null) { // Do stuff with your line here, it will be called for each // line of text in your file. } }
还有其他方法。 例如，如果文件不是太大而您只想将所有内容读取到单个字符串，则可以使用File.ReadAllText（）
myTextBox.Text = File.ReadAllText(fileName);
它只是一行代码：
string content = System.IO.File.ReadAllText(@"C:\textfile.txt");
试试这个：
if(result == DialogResult.OK && fileName != null) { try { var fileText=File.ReadAllText(fileName); } catch(Exception ex) { //Handle exception here } }
它会将所选文件中的所有数据读入fileText变量。
使用Split（），如下面的代码所示
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.IO; namespace ConsoleApplication1 { class Program { const string FILENAME = @"C:\temp\test.txt"; static void Main(string[] args) { StreamReader reader = new StreamReader(FILENAME); string inputLine = ""; List> data = new List>(); while ((inputLine = reader.ReadLine()) != null) { string[] inputArray = inputLine.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries); if (inputArray.Count() > 0) { List numbers = inputArray.Select(x => int.Parse(x)).ToList(); data.Add(numbers); } } } } }
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.IO; namespace part_B_19 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { try { StreamReader sr = new StreamReader(@"C:\Users\Acer\Documents\Visual Studio 2012\Projects\combobox.txt"); string line = sr.ReadLine(); while (line != null) { comboBox1.Items.Add(line); line = sr.ReadLine(); } } catch(Exception ex) { MessageBox.Show(ex.Message); } } } }
在C＃中演示FILE i / o的示例程序
class Items { public int itemID { get; set; } public string itemName { get; set; } public int itemNo { get; set; } public string pkgdate { get; set; } } class Program { private static string connectionString = "..."; static void Main(string[] args) { string streadpath = @"I:\itemdata.txt"; string stwritepath = @"I:\itemdata1.txt"; string stcopypath = @"I:\itemdata2.txt"; List li_all = new List (); List li_db = new List (); List li_valid = new List (); List li_invalid = new List (); li_all = stread_file(streadpath); li_invalid = validate(li_all); li_db = retrievefromDB(); bool x = stwrite_invalid(li_db, stwritepath); bool y = stcopy_file(streadpath, stcopypath); } static List stread_file(string stpath) { List stli = new List (); using (StreamReader SR = new StreamReader(stpath)) { string line = ""; while ((line = SR.ReadLine()) != null) { string[] linevalues = line.Split(','); Items obj = new Items(); obj.itemID = int.Parse(linevalues[0]); obj.itemName = linevalues[1]; obj.itemNo = int.Parse(linevalues[2]); obj.pkgdate = linevalues[3]; stli.Add(obj); } } return stli; } static List validate(List stli) { List li_valid = new List (); List li_invalid = new List (); DateTime parsed; foreach (Items stit in stli) { if(DateTime.TryParseExact(stit.pkgdate, "MM/dd/yyyy", CultureInfo.InvariantCulture, DateTimeStyles.None, out parsed)) { li_valid.Add(stit); } else { li_invalid.Add(stit); } } InsertDataToDb(li_valid); return li_invalid; } static bool stwrite_invalid(List stli,string stpath) { using (StreamWriter SW = new StreamWriter(stpath)) { foreach(Items stit in stli) { SW.WriteLine(stit.itemID + "," + stit.itemName + "," + stit.itemNo + "," + stit.pkgdate); } } return true; } static bool stcopy_file(string stsourcepath, string stdestinationpath) { File.Copy(stsourcepath, stdestinationpath); return true; } static void InsertDataToDb(List stli) { var records = stli; using (SqlConnection con = new SqlConnection(connectionString)) { StringBuilder nonQuery = new StringBuilder(); foreach (var item in records) { nonQuery.AppendFormat("INSERT INTO dbo.Smartphone VALUES ({0}, '{1}', {2}, '{3}');", item.itemID, item.itemName, item.itemNo, item.pkgdate); } SqlCommand cmd = new SqlCommand(nonQuery.ToString(),con); con.Open(); cmd.ExecuteNonQuery(); con.Close(); } } static List retrievefromDB() { List stli = new List (); DataTable dt = new DataTable(); SqlConnection con = new SqlConnection(connectionString); con.Open(); SqlCommand cmd = new SqlCommand("select * from dbo.Smartphone", con); SqlDataAdapter da = new SqlDataAdapter(cmd); da.Fill(dt); con.Close(); if (dt.Rows.Count > 0) { for (int i = 0; i < dt.Rows.Count; i++) { Items obj = new Items(); obj.itemID = (int)dt.Rows[i]["ID"]; obj.itemName = dt.Rows[i]["Name"].ToString(); obj.itemNo = (int)dt.Rows[i]["Num"]; obj.pkgdate = dt.Rows[i]["RDate"].ToString(); stli.Add(obj); } } return stli; } }
检查此代码：
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim myStream As Stream = Nothing Dim openFileDialog1 As New OpenFileDialog() 'openFileDialog1.InitialDirectory = "c:\" openFileDialog1.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*" openFileDialog1.FilterIndex = 1 openFileDialog1.RestoreDirectory = True If openFileDialog1.ShowDialog() = System.Windows.Forms.DialogResult.OK Then Try myStream = openFileDialog1.OpenFile() If (myStream IsNot Nothing) Then dataFile = openFileDialog1.FileName Label1.Text = openFileDialog1.SafeFileName Dim myReader As New StreamReader(dataFile) Dim line As String line = myReader.ReadLine() While Not (line Is Nothing) Dim str() As String = Split(line, ControlChars.Tab) ListView1.Items.Add(New ListViewItem(str)) line = myReader.ReadLine() End While myReader.Close() End If Catch Ex As Exception MessageBox.Show("Cannot read file from disk. Original error: " & Ex.Message) Finally ' Check this again, since we need to make sure we didn't throw an exception on open. If (myStream IsNot Nothing) Then myStream.Close() End If End Try End If End Sub