Name

Write Procedure

Syntax

procedure Write(var F: File; var Value; ...);
procedure Write(Expr:Width:Precision; ...);
procedure Write(var F: TextFile; Expr:Width:Precision; ...);

Description

The Write procedure writes text or other values to a file. If you are writing to a binary file, you must supply a variable of the same type as the file’s base type. You can write multiple records by listing multiple variables as arguments to the Write procedure.

When writing to a TextFile, you can write strings, numbers, characters, and Boolean values. Each value can be followed by the Width and Precision expressions, separated by colons. Width and Precision can be any integer expressions. Width specifies the minimum size of the string representation of Expr, and Precision specifies the number of places after the decimal point of a floating-point number.

Write uses as many characters as it needs, so Width is just the suggested minimum width. If the number requires fewer than Width characters, Write pads the string on the left with blanks. If you do not supply a Width, Delphi uses 1 as the minimum width for integers and it prints floating-point numbers as 26 characters in the following form:

'-1.12345678901234567E+1234'

If Expr is a floating-point number, Write reduces the number of decimal places to fit the value into a string that uses at most Width characters. Write always uses at least one digit after the decimal place, though. You can also supply a Precision, which tells Write how many decimal places to use after the decimal point. If you supply a Precision, Write uses fixed-point notation instead of exponential notation.

Tips and Tricks

  • If the file has not been assigned, Write reports I/O error 102.

  • If the file is not open for write access, Write reports I/O error 104.

  • When the write fails because the disk is full, sometimes Write reports the Windows error Error_Disk_Full (112); sometimes it reports I/O error 101.

  • If no file is given as the first argument, Write writes to the text file Output.

  • The Str procedure does the same thing as Write, except that it “writes” a single value to a string instead of a file.

Example

var
  D1, D2: TSomeRecord;
  F: File of TSomeRecord;
begin
  ...
  Write(F, D1, D2);

See Also

BlockWrite Procedure, File Keyword, IOResult Function, Output Variable, Read Procedure, Str Procedure, TextFile Type, WriteLn Procedure
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