Delphi in a Nutshell

Name

ReadLn Procedure

Syntax

procedure ReadLn(var F: TextFile; var Variable; ...);
procedure ReadLn(var Variable; ...);
procedure ReadLn(var F: TextFile);
procedure ReadLn;

Description

ReadLn is just like Read, but after it finishes reading into all the Variables, ReadLn skips the rest of the line and prepares to read the next line. Without any Variable arguments, ReadLn skips the rest of the line.

ReadLn cannot read a binary file. It is not a real procedure.

Tips and Tricks

• To ReadLn, a line ends when it reads a carriage return (#13) or reaches the end of file. The carriage return can optionally be followed by a linefeed (#10) or end of file.

• When reading strings, you almost certainly want to use ReadLn instead of Read. Calling Read to read a long string reads everything up to but not including the line ending. If you call Read again to read a string, it will read everything up to but not including the line ending, which means it reads an empty string. ReadLn reads the string and then skips the line ending, so you can read the next line of text into the next string.

• Without a TextFile as the first argument, ReadLn reads from Input.

Example

program bmindex;
// Compute a Body-Mass Index, given a person's height in centimeters
// and weight in kilograms. A BMI greater than 26 means a person
// is overweight.
var
  Height, Weight: Single;
  BMI: Integer;
begin
  WriteLn('Enter your height in centimeters: ');
  ReadLn(Height);
  WriteLn('Enter your weight in kilograms: ');
  ReadLn(Weight); BMI := Round((Weight ...