[next] [prev] [prev-tail] [tail] [up]

Blockread

Declaration:
Procedure Blockread (Var F : File; Var Buffer; Var Count : Longint [; var Result : Longint]);
Description:
Blockread reads count or less records from file F. A record is a block of bytes with size specified by the Rewrite (559) or Reset (558) statement.

The result is placed in Buffer, which must contain enough room for Count records. The function cannot read partial records. If Result is specified, it contains the number of records actually read. If Result isn’t specified, and less than Count records were read, a run-time error is generated. This behavior can be controlled by the {$i} switch.

Errors:
Depending on the state of the {$I} switch, a runtime error can be generated if there is an error. In the {$I-} state, use IOResult to check for errors.
See also:
Blockwrite (460), Close (465), Reset (558), Assign (455)

Listing: refex/ex6.pp

Program Example6;

{ Program to demonstrate the BlockRead and BlockWrite functions. }

Var Fin, fout : File;
    NumRead,NumWritten : Word;
    Buf : Array[1..2048] of byte;
    Total : Longint;

begin
  Assign (Fin, Paramstr(1));
  Assign (Fout,Paramstr(2));
  Reset (Fin,1);
  Rewrite (Fout,1);
  Total:=0;
  Repeat
    BlockRead (Fin,buf,Sizeof(buf),NumRead);
    BlockWrite (Fout,Buf,NumRead,NumWritten);
    inc(Total,NumWritten);
  Until (NumRead=0) or (NumWritten<>NumRead);
  Write ('Copied ',Total,' bytes from file ',paramstr(1));
  Writeln (' to file ',paramstr(2));
  close(fin);
  close(fout);
end.

[next] [prev] [prev-tail] [front] [up]