| Description |
If the current stream has not been exhausted, the next character, or block of characters are returned.
The stream position is updated accordingly.
In the first syntax, the Read method returns the next stream character is returned as an integer. The integer value is the numeric equivalent of the character, or -1 if the stream was exhausted. Carriage return and Line-feed characters are returned by this method.
In the second syntax, an attempt is made to read up to Count characters. These characters are overlaid onto the Characters array from StartIndex. The returned integer value is the number of characters overlaid. Zero if the stream was already exhausted before the read. Unlike StringReader, in this 2nd syntax, Carriage return and Line-feed characters are returned by this syntax.
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| | Notes | You must set the length of the target Character array in the second syntax, and it must have sufficient capacity to hold the returned characters.
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| Microsoft MSDN Links |
System.IO
System.IO.StreamReader
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| Reading a single character at a time |
program Project1;
{$APPTYPE CONSOLE}
uses
System.IO;
var
Reader : System.IO.StreamReader;
Writer : System.IO.StreamWriter;
CharAsInteger : Integer;
begin
// Create our Stream Writer to write to a text file
Writer := System.IO.StreamWriter.Create('C:\DelphiBasics.txt');
// Write various things to our StreamWriter
Writer.WriteLine('Hello');
Writer.WriteLine('World');
// Close the stream
Writer.Close;
// Read the stream
Reader := System.IO.StreamReader.Create('C:\DelphiBasics.txt');
while Reader.Peek >= 0 do
begin
CharAsInteger := Reader.Read;
if CharAsInteger = 13 // Carriage Return
then Console.Write('[CR]')
else if CharAsInteger = 10 // Line-feed
then Console.Write('[LF]')
else Console.Write(Char(CharAsInteger));
end;
Console.Readline;
end.
| | Show full unit code | Hello[CR][LF]World[CR][LF]
| | | Reading blocks of characters | program Project1;
{$APPTYPE CONSOLE}
uses
System.IO;
var
Reader : System.IO.StreamReader;
Writer : System.IO.StreamWriter;
CharArray : Array of Char;
CharCount : Integer;
CharAsInteger : Integer;
begin
// Create our Stream Writer to write to a text file
Writer := System.IO.StreamWriter.Create('C:\DelphiBasics.txt');
// Write various things to our StreamWriter
Writer.WriteLine('Hello');
Writer.WriteLine('World');
// Close the stream
Writer.Close;
// Read the stream
Reader := System.IO.StreamReader.Create('C:\DelphiBasics.txt');
// Create our target character array
SetLength(CharArray, 4);
// Read the characters from the stream in blocks
CharCount := Reader.Read(CharArray, 0, 4);
while CharCount > 0 do
begin
Console.WriteLine(CharCount.ToString +
' chars read : ' +
CharArray);
// Clear the char array before assigning into it
CharArray[0] := ' ';
CharArray[1] := ' ';
CharArray[2] := ' ';
CharArray[3] := ' ';
CharCount := Reader.Read(CharArray, 0, 4);
end;
Console.Readline;
end.
| | Show full unit code | 4 chars read : Hell
4 chars read : o
W // Includes line feed characters
4 chars read : orld
2 chars read : // Line feed characters
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