Ëåêöèéí çîðèëãî:

Íýã ôóíêöýýñ íºãºº ôóíêö óðóó ïàðàìåòð äàìæóóëàõ àðãóóä (õàÿãààð,óòãààð, òºëººëñºí íýðýýð) áîëîí òýäãýýðèéí òóñ òóñûí îíöëîãóóä, ÿìàð ¿åä õýðõýí õýðýãëýõ õýðýãëýý, õóâüñàã÷èéí óòãà àëäàãäàõ ýñ àëäàãäàõ ÷àíàðóóä, ¿ð ä¿í íü ÿìàð áàéõ, C++-èéí íýã îíöëîã áîëîõ õýä õýäýí èæèë  íýð á¿õèé äàõèí òîäîðõîéëîãäñîí ôóíêö-èéí õýðýãëýý ò¿¿íä òàâèãäàõ øààðäëàãóóä çýðãèéã ñóäàëæ ìýäýõ áîëíî.

1. Ôóíêöûí åðºíõèé ä¿ðñëýë

Ôóíêö áîë Ñ áîëîí C++-ûí ïðîãðàìûí ãîë á¿ðä¿¿ëýã÷ õýñýã þì. Ôóíêöûã á¿ðýí ä¿ðñëýë íü äîîðõ õýëáýðòýé áàéíà.

Áóöààõ_óòãûí_òºðºë  ôóíêöûí_ íýð(ïàðàìåòð¿¿ä)

{

Ôóíêöûí áèå

} 

Æèøýý íü:

Áóöààõ  

 óòãûí    Ôóíêöûí

 òºðºë       íýð                   

                                      Ýíý ôóíêö íü ïàðàìåòðã¿é

void greeting()

{

   printf("Hello");

}

  Ôóíêöûí áèå

Ôóíöûí ä¿ðñëýëä áóöààõ óòãûí òºðºë, ôóíêöûí íýð, ïàðàìåòð¿¿ä, ôóíêöûí áèå ãýñýí 4 ýëåìåíò îðîëöñîí áàéíà.

1.     Áóöààõ óòãûí òºðºë: Ôóíêö àæèëëàæ äóóñàõàä ÿìàð íýã óòãà áóöààãäàæ áîëíî. Ýíý áóöààãäàæ áóé óòãûí òºðëèéã ôóíêöûí íýðèéí ºìíº òóñãàéëàí çààæ ºãºõ ¸ñòîé.

2.     Ôóíêöûí íýð: Íýð íü çºâõºí ¿ñãýýð ýõëýñýí áàéõ ¸ñòîé áà ìºí òîî áîëîí äîîãóóð çóðààñ àãóóëæ áîëíî.

3.     Ïàðàìåòð¿¿ä : Ïàðàìåòð¿¿ä íü õîñ õààëòàí äîòîð áè÷èãäýíý. Õààëò íü ïàðàìåòð¿¿ä àãóóëààã¿é áàéñàí ÷ çààâàë áè÷èãäýõ ¸ñòîé. Ïàðàìåòðèéã áè÷èõäýý õóâüñàã÷èéí íýð áîëîí òºðëèéã òîäîðõîéëæ ºãíº. Ýíý íü äóóäàæ áóé ôóíêöýýñ óòãà õ¿ëýýí àâ÷ ò¿¿íèéãýý ôóíêö ð¿¿ äàìæóóëíà.

4.     Ôóíêöûí áèå: Ôóíêöûí ýõ áèåèéã ìºí õààëòàí äîòîð áè÷èæ ºãíº. 

2. Ôóíêöûí ïàðàìåòð¿¿ä

Ôóíêöûí ïàðàìåòð¿¿ä íü äóóäàæ áóé ôóíêöýýñ óòãà õ¿ëýýí àâ÷ ôóíêö ð¿¿ãýý äàìæóóëäàã. Ýõëýýä actual  ïàðàìàåòð áà formal ïàðàìåòð ãýñýí îéëãîëòûã àâ÷ ¿çüå. ¯íäñýí ïðîãðàìä áàéãàà ïàðàìåòðèéã actual, ôóíêöýä õýðýãëýãäýõ ïàðàìåòðèéã formal ïàðàìåòð ãýäýã.

                                          actual ïàðàìåòð¿¿ä    

Ôóíêöûã äóóäúÿ:                                       number(var1, var2);

Ôóíêöûí çàðëàëò:                                     void number(int x, float y) 

                                       formal ïàðàìåòð¿¿ä                                                     

Ñ-ä íýã ôóíêöýýñ íºãºº ð¿¿ àðãóìåíòèéã óòãààð áîëîí õàÿãààð äàìæóóëäàã.

Ñ++- íü ýíý õî¸ð áîëîìæèéã àãóóëñàí áà íýã íýìýëò øèíý áîëîìæîîð õàíãàãäñàí áàéäàã. Ýíý íü çààëò áóþó õóâüñàã÷èéí òºëººëñºí íýðýýð óòãà äàìæóóëíà.

Ôóíêö ð¿¿ óòãààð àðãóìåíò äàìæóóëàõ ¿åä óòãûã õ¿ëýýí àâñàí ôóíêö ò¿¿íèéã ººð÷èëñºí ÷ ôóíêöûí ýõ óòãà ººð÷ëºãäºõã¿é. Õàðèí õàÿã àâàõ & îïåðàòîðûã àøèãëàí õóâüñàã÷èéí õàÿãèéã äàìæóóëàõ, ìºí çààã÷ûí îíöãîé òºðºë áîëîõ çààëòûã àøèãëàñíààð ôóíêöûí ýõ óòãàä ººð÷ëºëò õèéæ ÷àäíà.

Áèä äàðààãèéí  ñýäâ¿¿äýýð ÿàãààä èéì áàéíà âý ãýäãèéã íýã á¿ð÷ëýí äýëãýð¿¿ëýí àâ÷ ¿çýõ áîëíî.

3. Ôóíêöýä ïàðàìåòðèéã õóâüñàã÷ààð äàìæóóëàõ

Ñêàëÿð òºðºëòýé õóâüñàã÷äèéã  ôóíêöýä äàìæóóëàõàä, ôóíêöýä ò¿¿íèé õóóëáàð õóâüñàã÷èä äàìæèãääàã. Ôóíêö òýð õóóëáàð äýýð íü ¿éëäëèéã õèéíý. Æèøýýí äýýð õàðóóëüÿ:

void check( float f, int i=10, char p[]="char”)         //  formal  ïàðàìåòð

{ cout<<f;

   cout<<i;

   cout<<p;}

ôóíêö 1:    void check   (  float f,   int i=10,   char p [ ] = "char”)

                óòãà                   àíõíû                    àíõíû

            áóöààõã¿é            óòãàã¿é                 óòãàòàé

  à)  check ôóíêöèéã (1.5, 7) ãýæ äóóäàõàä  f = 1.5,   i =7 áîëîõ áà   ð íü øóóä àíõíû óòãàà àâíà.

  á) check ôóíêöèéã (4.5, 20, "ÐÎД) ãýæ äóóäàõàä  f = 4.5,   i =20   ð="POP”  áîëíî.

  â) check ôóíêöèéã (1) ãýæ äóóäàõàä  f = 1 áîëîõ áà íºãºº 2 ïàðàìåòð íü àíõíû óòãàà øóóä àâíà. Õàðèí ÿìàð ÷ àðãóìåíò äàìæóóëàõã¿éãýýð ôóíêöèéã äóóäâàë àëäàà ºãíº.

  ã) float f =9.5;     int i = 5;  check ( f, i ) ãýæ ôóíêöèéí formal ïàðàìåòðèéí íýðòýé èæèë äóóäàæ áîëîõ áîëîâ÷ ïàðàìåòðûí çºâõºí õóóëáàð íü äàìæèãäàõ ó÷èð actual ïàðàìåò𠺺ð÷ëºãäºõã¿é. ̺í actual áîëîí formal ïàðàìåòð¿¿ä èæèë íýðòýé áàéæ áîëíî.

 ä)  Ôóíêö äóóäàõäàà õóâüñàã÷èéí òºðëèéã õóâèðãàí äóóäàæ áîëíî.

check( (char) f, (char) I, "”) ãýæ äóóäâàë f = 9,   i =5   ð=" ”  áîëíî.

Äîîðõ æèøýýã ñîíèðõîæ ¿çüå.

  VaraP1.cpp

#include<iostream.h>

void number(int too);

void main()

{

   int i=10;

   cout<<"Value of  i  is"<<i<<endl;

   number(i);

  cout<<"Value of  i  is"<<i<<endl;

}

void number(int too)

{  cout<<"Value of too is"<<too<<endl;

   too*=3;

  cout<<"Value of too is"<<too<<endl;

}

Ïðîãðàìûí ¿ð ä¿í:

Value of i is 10                                                          // (1)

Value of too is 10                                                      // (2) 

Value of too is 30                                                      //(3)

Value of i is 10                                                          //(4)  

(1)-ð ìºðºíä i ûí ýõ ôóíêö äýõ óòãûã 10 ãýæ õýâëýñýí áàéíà. number ôóíêöýä i   ûí óòãûã äàìæóóëæ óòãûã íü ººð÷èëñºí áîëîâ÷  ( (3)-ð ìºð ) main() ôóíêöýýñ äàõèí õýâëýõýä ýõ óòãàä ÿìàð íýãýí ººð÷ëºëò îðîîã¿é áàéíà.

Ó÷èð íü ôóíêö ð¿¿ àðãóìåíòûã óòãààð äàìæóóëàõàä óã ôóíêöýä çºâõºí óòãûí õóóëáàðûã äàìæóóëäàã. ªºðººð õýëáýë ôóíêö íü ºãºãäëèéí õóóëáàðûã ñàíàõ îéí ººð õýñýãò áàéðëóóëæ òýð õóâèëáàð äýýðýý àæèëëàíà. Ôóíêö äîòîð óã àðãóìåíòûí õóóëáà𠺺ð÷ëºãäºíº ¿¿ ãýõýýñ àctual ïàðàìåòðò ÿìàð íýã ººð÷ëºëò¿¿ä íºëººëºõã¿é. 

    VaraP2.cpp

#include<iostream.h>

void fun (int val);

void main()

{

    int val=10;

    cout<<”ôóíêö äóóäàõààñ ºìíºõ val-èéí óòãà:”<<val<<endl;

    fun(val);                                                                 //val-èéí óòãûã äàìæóóëàõ

    cout<<”ôóíêöýýñ áóöàæ èðñíèé äàðààõ val-èéí óòãà:”<<val<<endl;

}

void fun(int val)                                                      //val-èéí óòãûã õ¿ëýýæ àâàõ

{   val+=7;                                                               //óòãàí äýýð 7-ã íýìýõ

      cout<<”ôóíêö äîòîðõ val-èéí óòãà:”<<val<<endl;

}                                                                                                                   

Ïðîãðàìûí ¿ð ä¿í:

 ôóíêö äóóäàõààñ ºìíºõ val-èéí óòãà: 10

 ôóíêö äîòîðõ val-èéí óòãà:17

 ôóíêöýýñ áóöàæ èðñíèé äàðààõ val-èéí óòãà:10

                                            val                   10          

                                 val(õóóëáàð)            10+7

4. Ôóíêöýä ïàðàìåòðèéã çààã÷ààð áóþó õàÿãààð äàìæóóëàõ

Áóñàä õóâüñàã÷äûí àäèë çààã÷ íü ôóíêöûí àðãóìåíò áîëæ ÷àäíà. Çààã÷ûã ôóíêöûí àðãóìåíò áîëæ àøèãëàõ íü îíöãîé à÷ õîëáîãäîëòîé. Ó÷èð íü õàÿã àâàõ & îïåðàòîðûã àøèãëàí óòãà äàìæóóëàõàä ôóíêöûí êîä äîòîð àðãóìåíòûí óòãûã ººð÷èëñºí ººð÷ëºëò íü main() ôóíêö äýõ ýõ óòãàíä ººð÷ëºëò îðóóëíà. ßàãààä  ãýâýë  ýíý  ¿åä  õî¸ð  ôóíêö  íü íýã  õóâüñàã÷òàé  àæèëëàæ  áàéãàà  þì.

Ôóíêöýä ïàðàìåòðèéã õàÿãààð äàìæóóëàõàä formal ïàðàìåòð íü actual ïàðàìåòðèéí õàÿãèéã àâíà. 

Ñêàëÿð õóâüñàã÷èéí õàÿãèéã äàìæóóëàõäàà ( int, long, float ã.ì ìàññèâ áèø ºãºãäëèéí òºðë¿¿äèéã ñêàëÿð õóâüñàã÷èä ãýäýã. ) & îïåðàòîðûã àøèãëàõ íü ç¿éòýé.

Õàðèí ìàññèâûí íýð íü óã ìàññèâûí ñàíàõ îéä áàéðëàõ ýõëýëèéí õàÿã áàéäàã ó÷èð ìàññèâûí õàÿã äàìæóóëàõ ¿åä & îïåðàòîðûã àøèãëàõ õýðýãã¿é. Õ¿ëýýí àâñàí ôóíêö íü ìàññèâò ººð÷ëºëò õèéõýä ýõ ôóíêö äýõ óòãà íü ìºí ººð÷ëºãäºíº.