从字符串更改为整数

Question

EveryOne I need some esay way to change from integer and string in delphi 7

var 
Str:String;
Int:Integer;
// Here what i need to do
Str:='123';
Int:=Str.AsInteger
// or use this
Int:=123;
Str=Int.AsString;

Answer 1

The easiest way is to use these two methods:

IntVal := StrToInt(StrVal);    // will throw EConvertError if not an integer
StrVal := IntToStr(IntVal);    // will always work

You can also use the more fault-tolerant TryStrToInt (far better than catching EConvertError ):

if not TryStrToInt(StrVal, IntVal) then
  begin
  // error handling
  end;

If you want to resort to a default value instead of handling errors explictly you can use:

IntVal := StrToIntDef(StrVal, 42);    // will return 42 if StrVal cannot be converted

Answer 2

If you're using a recent version of Delphi, in addition to the previous answers, you can alternatively use a pseudo-OOP syntax as you wanted to originally - the naming convention is just ToXXX not AsXXX:

Int := Str.ToInteger
Str := Int.ToString;

The Integer helper also adds Parse and TryParse methods:

Int := Integer.Parse(Str);
if Integer.TryParse(Str, Int) then //...

Answer 3

You can use:

StrToInt(s)

and

IntToStr(i)

functions.

Answer 4

type 
TForm1 = class(TForm) 
Button1: TButton; 
Edit1: TEdit; 
procedure Button1Click(Sender: TObject); 
end; 

Integer = class 
FValue: System.Integer; 
function ToString: string; 
public 
property Value: System.Integer read FValue write FValue; 
end; 

var 
Form1: TForm1; 

implementation 

function Integer.ToString: string; 
begin 
Str(FValue, Result); 
end; 

procedure TForm1.Button1Click(Sender: TObject); 
var 
Int:integer; 
begin
Int.Value:=45; 
Edit1.Text:=Int.ToString; 
end; 
end