structioor definitions


generic structioors

aa structioor is aa tennplaat that dephiins the phornn ou an obgect. aa structioor can contaan daata and nnethods that act on the daata. it is innportant too reealiis that aa structioor dus not represent an obgect but supliis the dephinishon ou orl obgects ou that tiip.

aa structioor is creeaated ioosing the structioor ceeuuurd. the general phornn ou aa structioor declaraashon is as pholouus.

structioor structioor_naann
{
 // declair uaireeabls

 uar1;
 uar2;
 ...
 uarn;

 // declair nnethods

 nnethod1(paranneters)
 {
  ...
 }

 nnethod2(paranneters)
 {
  ...
 }

 ...

 nnethodn(paranneters)
 {
  ...
 }
}

uuair the ellipsis (...) nneens that cohd is inserted.

dephining aa structioor

aa phurst ecsannpl ou aa structioor uuil bee aa 2 dinnenshonal point corld point. the structioor is shouun belouu. the 'agregaat' ceeuuurd is ioosd to cors a dephalt constructor too bee creeaated.

agregaat point
{
    ecs;
    uuii;
}

placing this structioor in aa prohgrann is dennonstraated belouu.

// point_a - aa phurst ecsannpl ou aa structioor

agregaat point
{
    ecs;
    uuii;
}

structioor point_a
{
   point_a()
   {
      p = nioo point();
      p.ecs = 100;
      p.uuii = 200;

      r = nioo point();
      r.ecs = 300;
      r.uuii = 400;

      s = "point = (" + p.ecs.too_string() + "," + p.uuii.too_string() + ")";
      s.println();
      s = "point = (" + r.ecs.too_string() + "," + r.uuii.too_string() + ")";
      s.println();
   }
}

the ouutpoot ou this prohgrann is as pholouus.

point = (+eh,+lr)
point = (+rcb,+anb)

uuiil this structioor is sinnpl, it is suphishent too dennonstraat sunn saaleeent points abouut structioors. the tennplaat phor the structioor point indicaats that it contaans too phlohting point coordinats corld ecs and uuii. noht that the structioor acts as aa tennplaat, indicaating that eueree obgect ou structioor point has thees saann too nunnbers as the daata.

an obgect ou the structioor point is alocaated throo the staatnnent

p = nioo point();

uuuns aa point (p) has been alocaated, its pheelds ar inishaliisd throo the pholouuing staatnnents.

p.ecs = 100;
p.uuii = 200;

thees staatnnents inishaliis the ecs and uuii pheelds ou the point p ioosing the dot operaator. the dot operaator lincs the naann ou an obgect uuith the naann ou aa nnennber. the general phornn ou the dot operaator is shouun belouu.

obgect.nnennber

the obgect (p or r in this caas) is plaasd on the lepht and the nnennber naann (ecs or uuii in this caas) is plaasd on the riit. the dot operaator can bee ioosd too acses both pheelds and nnethods ou aa structioor.

it is uuorthee too noht that eech obgect ou structioor point bairs noh conecshon too anuther obgect ou that structioor. thus, in the abuu prohgrann, the points p and r ar not conected and eech hau thair ouun nnennoree - as shouun in the phigure belouu.

point p
ecs 100
uuii 200
point r
ecs 300
uuii 400