CS 201 - 8/26/2014

Programming Basics - Chapter 1

Source code files:
   text files with the code
   C program   xxxx.c
   C++ program xxxx.cpp

CS201 will not cover objects

Create an object file from the source code file
   object files   xxxx.o


Executable file
     On windows:    xxxx.exe
     On Linux:      xxxx
     Default Linux: a.out


Compilation process
 1.  Preprocessor
 2.  Compiliation   - create the object files
 3.  Linking        - create the executable files


Preprocessor items:

  #define
  #include  
  #ifdef
  #ifndef
  #endif
  
Mostly for libraries
  #include  <stdio.h>       /* C style library */
  #include  <iostream>      /* C++ style library */

imports the function signatures of the library operations

   function signatures
     - name of the function
     - number, type and order of the parameters
     - return type



int max (int p1, int p2)
{
  ...
  return z;
}

int main ()
{
  int a,b,c

  a = max (b, c);  

}
=========================
int max (int, int);  /* prototype or forward declaration */

int main ()
{
  int a,b,c

  a = max (b, c);  
}

int max (int p1, int p2)
{
  ...
  return z;
}


----------------------------
#define  - C style constant

#define MAX 1000


   for (i = 0 ; i < MAX  ; i++)
     { .... }

In C++ #define was replaced with const

   const int MAX = 1000;

#define MAX(x,y) x>y?x:y

      a = MAX(b,c);

      a = b>c ? b : c ;

      b = 10; c = 3;
      a = 2 * MAX(b+1,c+2)

      a = 2* b+1>c+2 ? b+1 : c+2;

#define SIX 1+5
#define NINE 8+1

    SIX * NINE

    1 + 5 * 8 + 1

-----------------------------------
#ifdef
#ifndef
#endif

-------------------------------------------

C pointers
- first item parameter passing

       pass-by-value
       pass-by-reference
 int main()
  {
   int a;
   a = 10;
   funct1 (a);
   funct2 (&a);
  }
   ----------------
   funct1 ( int p1)
    {
      p1 = p1 + 5;
    }
   ----------------
   funct2 ( int* p1)  /* pass by address */
    {
      printf ("%d", *p1);
      *p1 = *p1 + 5;
    }