Thủ tục hoán đổi.

PROGRAM CT83;
USES crt;
VAR a,b: INTEGER;
PROCEDURE HoanDoi(VAR x,y: INTEGER);
VAR t: INTEGER;
BEGIN
Writeln(x,' ',y);
t:=y; y:=x; x:=t;
Writeln(x,' ',y);
END;
BEGIN
clrscr;
Write('Nhap 2 so : '); Readln(a,b);
HoanDoi(a,b);
Readln
END.

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