Question

delphi 疑问：incompatible types string and extended

新写了个 delphi 程序 ：

unit test3001;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;

type
TForm1 = class(TForm)
Label1: TLabel;
Edit1: TEdit;
Edit2: TEdit;
Edit3: TEdit;
Button1: TButton;
Button2: TButton;
procedure button1click(Sender: TObject);
procedure Button2Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.button1click(Sender: TObject);
var
a,b,c,s,area,real,str1:string;

begin
a:=strtofloat(Edit1.Text);
b:=strtofloat(Edit2.Text);
c:=strtofloat(Edit3.Text);
s:=(a+b+c)/2;
area:=sqrt(s*(s-a)*(s-b)*(s-c));
str(area:8:3,str1);
showmessage('面积为：'+str1);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
edit1.Text:='';
edit2.Text:='';
edit3.Text:='';

end;

end.

run的时候报错：incompatible types string and extended

请问大家应该如何解决阿？

Answer 1

procedure TForm1.button1click(Sender: TObject);
var
a,b,c,s,area,real,str1:real; //这里要改

begin
a:=strtofloat(Edit1.Text);
b:=strtofloat(Edit2.Text);
c:=strtofloat(Edit3.Text);
s:=(a+b+c)/2;
area:=sqrt(s*(s-a)*(s-b)*(s-c));
str(area:8:3,str1);
showmessage('面积为：'+floattostr(str1));//这里要改
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
edit1.Text:='';
edit2.Text:='';
edit3.Text:='';

end;

end.

这样应该没问题了,写程序的时候注意变量的类型,delphi是不会自动转换类型的,你定义成了字符串型,再给他付实数值,当然报错了.