test28, Pascal - rextester

test28

program test28;
{pointer example of direct chain growth and key inf change}
type spisok=^elem;
    elem=record
            inf:real ;
            sled:spisok
            end ;
label 1,2;
const M:integer = 5;
var a, pervy,d,l: spisok ;
    mas: array[1..5] of integer ;
    i,r:integer ;
    b:boolean;
procedure sostavlenie2(var p1:spisok; N:integer) ;
var q,p2:spisok ;
    
begin
    New(q) ; {data generator}
    p1:=q; {head safe}
    p2:=q;
for i :=1 to N do
  begin
    q^.inf:=mas[i] ;
    q^.sled:=Nil;
    p2^.sled:=q;
    p2:=p2^.sled;
    New(q);
  end ;
end ;
 begin
     M:=5;
     for i:=1 to M do
     mas[i]:=i ;
    sostavlenie2(pervy, M) ;
    a:=pervy ;
    l:=a;
    r:=0;
    b:=true;
    New(d); {make new element}
    d^.inf:=10;
    d^.sled:=Nil;
while (a<> nil) and b do
     if a^.inf=3 then {appoint the element}
     begin
        b:=false; {key inf achieved}
        if r>1 then for i:=1 to r-1 do l:= l^.sled;
        l^.sled:=d;
        d^.sled:=a^.sled; {change appointed element with new element "d"}       
     end
      else  begin a:=a^.sled;
                  if a=Nil then goto 1 ;
                  r:=r+1;      
            end;
      begin
            writeln('Appointed element is ',a^.inf:2:1) ; {show appointed element}
            writeln;
            a:=pervy;
            repeat 
                  writeln(a^.inf:2:1) ;
                  a:=a^.sled;
            until a=Nil;
                  goto 2 ;
       end;
1: writeln('no such key info element');
2:end.


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