Add File Input Output in Pascal (TheRenegadeCoder#4831)

Author: pascalecu

archive/p/pascal/file_input_output.pas

@@ -0,0 +1,87 @@
+program FileIO;
+
+{$mode objfpc}{$H+}
+
+uses
+   SysUtils;
+
+const
+   DefaultFileName = 'output.txt';
+
+function WriteToFile(const FileName: string): integer;
+var
+   F: TextFile;
+begin
+   Result := 1; // failure by default
+   try
+      AssignFile(F, FileName);
+      Rewrite(F);
+
+      try
+         Writeln(F, 'A line of text');
+         Writeln(F, 'Another line of text');
+         Result := 0; // success
+      finally
+         CloseFile(F);
+      end;
+   except
+      on E: Exception do
+      begin
+         Writeln('Error writing to file "', FileName, '": ', E.Message);
+      end;
+   end;
+end;
+
+function ReadFromFile(const FileName: string): integer;
+var
+   F: TextFile;
+   Line: string;
+   LinesRead: integer;
+begin
+   Result := 1; // failure by default
+   LinesRead := 0;
+   try
+      AssignFile(F, FileName);
+      Reset(F);
+
+      try
+         while not EOF(F) do
+         begin
+            ReadLn(F, Line);
+            Writeln(Line);
+            Inc(LinesRead);
+         end;
+         if LinesRead = 0 then
+            Writeln('(File "', FileName, '" is empty)');
+         Result := 0; // success
+      finally
+         CloseFile(F);
+      end;
+   except
+      on E: Exception do
+      begin
+         Writeln('Error reading from file "', FileName, '": ', E.Message);
+      end;
+   end;
+end;
+
+var
+   FileName: string;
+begin
+   FileName := DefaultFileName;
+
+   if WriteToFile(FileName) <> 0 then
+   begin
+      ExitCode := 1;
+      Exit;
+   end;
+
+   if ReadFromFile(FileName) <> 0 then
+   begin
+      ExitCode := 1;
+      Exit;
+   end;
+
+   ExitCode := 0;
+end.
+