42                                2.     

 iostream.h,     . 
 D, -        -
 -.    ,    
     .

 iostream     :

     //   
     //   

 ,      :

cout   //  

 in    //  

   //  

        -
:

  io.cpp

int i ;

double x;

cout  "\    : ";

 in  ;

cout  "\  : ";

cin  i;

if (i < 1)

cerr  ", i = "  i  end.1;

cout  "i * x = "  i * x;

  ( )    .  
  ,        -
   .     -
,     ,     -
     .  -   .
 ,       -
   .    . -
,  i   -1,      :

, i = -1

 endl  .    cerr  -
  .     i *  =,    -
  i * .

2.3.  

  C++      .    -
;   ,   ,  -
    .     (call-by-value),   -