private string[ ] ReadAllLines( string path, Encoding encoding ) 
{
    StringCollection coll = new StringCollection( );

    using ( StreamReader sr = new StreamReader( path, encoding ) ) 
    {
        string line;

        while ( ( line = sr.ReadLine( ) ) != null ) 
        {
            coll.Add( line );
        }
    }


    string[ ] lines = new string[ coll.Count ]; 
    coll.CopyTo( lines, 0 );
    return lines; 
}

Option Explicit
Private Sub ReadAllLines(ByVal sPath As String, ByRef aLines() As String)
Dim FF As Integer
Dim sBuffer As String
    FF = FreeFile
    On Error Resume Next
    Open sPath For Input As #FF
        sBuffer = Input(LOF(FF), #FF)
    Close #FF
    aLines = Split(sBuffer, vbNewLine)
End Sub


' exemple d'utilisation
Private Sub Form_Load()
Dim aMesLignes() As String
Dim i As Long
    Me.AutoRedraw = True
    Me.Show
    
    ReadAllLines "a:\log.txt", aMesLignes
    Me.Print (1 + UBound(aMesLignes)) & " lignes trouvées" & vbNewLine
    For i = LBound(aMesLignes) To UBound(aMesLignes)
        Me.Print aMesLignes(i)
    Next i
End Sub

function ReadAllLines ($sFileName) { // PHP4 et PHP5; retourne une chaîne
  if (file_exists ($sString)) {
    return file_get_contents ($sFileName);
  } else {
    return false;
  }
}
function ReadAllLines ($sFileName) { // PHP3, PHP4 et PHP5; retourne un tableau dont chaque entrée est une ligne du fichier
  if (file_exists ($sString)) {
    return file ($sFileName);
  } else {
    return false;
  }
}

Dim fileContents As String
fileContents = My.Computer.FileSystem.ReadAllText("C:\Test.txt")

//ajout à propos du code de malam :
function read_filr_2_string($fichier){
return implode('', file($fichier));
}

//jdk 1.4.x et inferieur
 
 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileReader;
 
 String lineSep = System.getProperty("line.separator");
 String name = "fichier.txt";
 try{
     BufferedReader r = new BufferedReader(new FileReader(new File(name)));
     String s = "";
     String result = "";
     while((s = r.readLine()) != null) result += (s+lineSep);
     r.close();
     System.out.println(result);
 }catch(Exception e){
     e.printStackTrace();
 }
 
 //jdk 1.5.x et superieur
 
 import java.io.File;
 import java.io.FileReader;
 import java.util.Scanner;
 
 String lineSep = System.getProperty("line.separator");
 String name = "fichier.txt";
 try{
     String result = "";
     Scanner s = new Scanner(new FileReader(new File(name)));
     while(s.hasNext())result += (s.nextLine() + lineSep);
     System.out.println(result);
 }catch(Exception e){
     e.printStackTrace();
 }