How to swap between two arrays in Delphi?-CodePudding

How to swap between two arrays in Delphi?

Just like the following function

 
Procedure swap (var I and j: integer); 
Var 
I, j, TMP: integer; 
The begin 
TMP:=I; 
I:=j; 
J:=TMP; 
end;

CodePudding user response:

Set an intermediate variable or array, read cycles

CodePudding user response:

reference 1st floor PTVBS response:

set an intermediate variable or array, loop read

In addition to the circulation, do you have any other methods?
Because multiple exchange array and array elements is more,
Loop speed will be slow,

CodePudding user response:

Exchanging data with intermediate buffer,

Var
ArrList0: an array of byte [0.. 5];
ArrList1: an array of byte [0.. 5];
ArrTemp: an array of byte [0.. 5];

//memory replication
Fillchar (arrtemp, 6, 0);
Move (pbyte (@ arrlist0 [0]) ^ and pbyte (@ arrtemp [0]) ^, 6);
Move (pbyte (@ arrlist1 [0]) ^ and pbyte (@ arrlist0 [0]) ^, 6);
Move (pbyte (@ arrtemp [0]) ^ and pbyte (@ arrlist1 [0]) ^, 6);

CodePudding user response:

Procedure TForm1. Hmary (var mary1 mary2: an array of string);
Var
Mary: an array of string;
I: Integer;
The begin
SetLength (Mary, High (mary1));
For I:=0 to high do (mary1) - 1
The begin
Mary: [I]=mary1 [I];
Mary1 [I] :=mary2 [I];
Mary2 [I] :=Mary [I];
end;
end;
Swap process

CodePudding user response:

Fix it: for I:=0 to high (mary1) do

Hight (mary1) should not be minus 1

CodePudding user response:

Note that Delphi is a 4 gl, its intelligent degree is high, the same type of the array can direct assignment, the compiler generates code processing elements replication problem (copy may only be a pointer, if is a dynamic array), and does not require users to worry about,
Note:
Type
TByteArray10=array [0.. 9] of byte;
Var
A1, a2, a3: an array of byte [0.. 9];//this is the same type
A4: an array of byte [0.. 9].//
A5: an array of byte [0.. 9];//
A6: an array of byte [0.. 9];//is not the same type, but can be cast with TByteArray10

Can direct assignment exchange like this:
A3:=a1;
A1:=a2;
A2:=a3;
TByteArray10 (a6) :=TByteArray10 (a4);
TByteArray10 (a4) :=TByteArray10 (a5);
TByteArray10 (a5) :=TByteArray10 (a6);

CodePudding user response:

refer to 6th floor DelphiGuy response:

note that Delphi is a 4 gl, it is a high degree of intelligence, the same type of the array can direct assignment, the compiler generates code processing elements replication problem (copy may only be a pointer, if is a dynamic array), and does not require users to worry about,
Note:
Type
TByteArray10=array [0.. 9] of byte;
Var
A1, a2, a3: an array of byte [0.. 9];//this is the same type
A4: an array of byte [0.. 9].//
A5: an array of byte [0.. 9];//
A6: an array of byte [0.. 9];//is not the same type, but can be cast with TByteArray10

Can direct assignment exchange like this:
A3:=a1;
A1:=a2;
A2:=a3;
TByteArray10 (a6) :=TByteArray10 (a4);
TByteArray10 (a4) :=TByteArray10 (a5);
TByteArray10 (a5) :=TByteArray10 (a6);

Whether the dynamic array can also handle?
So I use an Error (Error) Unit1. Pas (131) : Invalid typecast

 
Type 
TArrInt=array of integer; 

Procedure Swap (var x, y: an array of integer); 
Var 
TMP: an array of integer; 
The begin 
TArrInt (TMP) :=TArrInt (x); 
TArrInt: (x)=TArrInt (y); 
TArrInt: (y)=TArrInt (TMP);

CodePudding user response:

Unable to process the incoming parameter

CodePudding user response:

 
Procedure Swap (x, y: an array of integer); 
Type 
TByteArray10=array of integer; 
Var 
A1, a2, a3: an array of integer;//this is the same type 
A4: an array of integer;//
A5: an array of integer;//
A6: an array of integer;//is not the same type, but can be cast with TByteArray10 
The begin 
//can direct assignment exchange like this: 
A3:=a1; 
A1:=a2; 
A2:=a3; 
TByteArray10 (a6) :=TByteArray10 (a4); 
TByteArray10 (a4) :=TByteArray10 (a5); 
TByteArray10: (x)=TByteArray10 (a6);//this compilation times wrong: Invalid typecast 
end;

CodePudding user response:

Procedure Swap (var x, y: an array of integer); The statement of x, y type is not a dynamic array, but the open array parameter, this type of compatible static array parameters, dynamic array, to [] array of temporary structure, so the x, y actual type is not necessarily the same,
It is ok to like this:
Type
TArrInt=array of integer;

Procedure Swap (var x, y: TArrInt);
Var
Z: TArrInt;
The begin
Z:=x;
X: y=;
Y:=z;
end;

CodePudding user response:

The

references to the tenth floor DelphiGuy response:

procedure Swap (var x, y: an array of integer); The statement of x, y type is not a dynamic array, but the open array parameter, this type of compatible static array parameters, dynamic array, to [] array of temporary structure, so the x, y actual type is not necessarily the same,
It is ok to like this:
Type
TArrInt=array of integer;

Procedure Swap (var x, y: TArrInt);
Var
Z: TArrInt;
The begin
Z:=x;
X: y=;
Y:=z;
end;

Why
So you can compile

 
Procedure TForm1. Btn4Click (Sender: TObject); 
Type 
TByteArray=an array of byte; 
Var 
A1: an array of byte; 
A2: an array of byte; 
A3: an array of byte;//a1, a2, a3 is not the same type, but can be cast with TByteArray10 
The begin 
TByteArray (a3) :=TByteArray (a1); 
TByteArray (a1) :=TByteArray (a2); 
TByteArray (a2) :=TByteArray (a3); 
End

And that will not be able to compile

 
Procedure Swap2 (x, y: an array of integer); 
Type 
nullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnull