Oxygen Basic

Information => Reference => Topic started by: Charles Pegge on August 10, 2011, 07:40:13 AM

Title: C Lessons
Post by: Charles Pegge on August 10, 2011, 07:40:13 AM

I'm taking some time out to study C with a view to making tools for cross platform devlopment. I was surprised to find that GCC works without any switches. I have MinGW installed, and all it needs is:

bin\gcc prog.c

and voila! It compiles to a.exe by default

Here is my crash course so far. C material is very easy to find on the web.


C Source 1

Code: C

1.   int main()
2.   {
3.     return 0;
4.   };
5.  

C Source 2

Code: C

1.   #include <stdio.h>
2.  
3.   int main()
4.   {
5.     // int a;
6.     printf ("Hello World!\n");
7.     return 0;
8.   };

C Source 3

Code: C

1.  
2.   /* malloc example: string generator*/
3.  
4.   #include <stdio.h>
5.   #include <stdlib.h>
6.  
7.   int main ()
8.   {
9.   int i,n;
10.   char * buffer;
11.  
12.   printf ("How long do you want the string? ");
13.   scanf ("%d", &i);
14.  
15.   buffer = (char*) malloc (i+1);
16.   if (buffer==NULL) exit (1);
17.  
18.   for (n=0; n<i; n++)
19.     buffer[n]=rand()%26+'a';
20.   buffer[i]='\0';
21.  
22.   printf ("Random string: %s\n",buffer);
23.   free (buffer);
24.  
25.   return 0;
26.   };
27.  

C Source 4

Code: C

1.   // http://www.cplusplus.com/reference/clibrary/cstdio/scanf/
2.  
3.   /* scanf example */
4.   #include <stdio.h>
5.  
6.   int main ()
7.   {
8.   char str [80];
9.   int i;
10.  
11.   printf ("Enter your family name: ");
12.   scanf ("%s",str);  
13.   printf ("Enter your age: ");
14.   scanf ("%d",&i);
15.   printf ("Mr. %s , %d years old.\n",str,i);
16.   printf ("Enter a hexadecimal number: ");
17.   scanf ("%x",&i);
18.   printf ("You have entered %#x (%d).\n",i,i);
19.  
20.   return 0;
21.   }
22.  
23.  

C Source 5

Code: C

1.   // http://www.cplusplus.com/reference/clibrary/cstdio/fopen/
2.  
3.   /* fopen example */
4.   #include <stdio.h>
5.   int main ()
6.   {
7.   FILE * pFile;
8.   pFile = fopen ("myfile.txt","w");
9.   if (pFile!=NULL)
10.   {
11.     fputs ("fopen example",pFile);
12.     fclose (pFile);
13.   }
14.   return 0;
15.  }
16.  

C Source 6

Code: C

1.   // http://www.cplusplus.com/reference/clibrary/cstdio/setbuf/
2.  
3.   /* setbuf example */
4.   #include <stdio.h>
5.  
6.   int main ()
7.   {
8.   char buffer[BUFSIZ];
9.   FILE *pFile1, *pFile2;
10.  
11.   pFile1=fopen ("myfile.txt","w");
12.   pFile2=fopen ("myfile2.txt","a");
13.  
14.   setbuf ( pFile1 , buffer );
15.   fputs ("This is sent to a buffered stream",pFile1);
16.   fflush (pFile1);
17.  
18.   setbuf ( pFile2 , NULL );
19.   fputs ("This is sent to an unbuffered stream",pFile2);
20.  
21.   fclose (pFile1);
22.   fclose (pFile2);
23.  
24.   return 0;
25.   }
26.  

C Source 7

Code: C

1.   // http://www.cplusplus.com/reference/clibrary/cstdio/fread/
2.  
3. /* fread example: read a complete file */
4. #include <stdio.h>
5. #include <stdlib.h>
6.  
7. int main () {
8.   FILE * pFile;
9.   long lSize;
10.   char * buffer;
11.   size_t result;
12.  
13.   pFile = fopen ( "myfile.bin" , "rb" );
14.   if (pFile==NULL) {fputs ("File error",stderr); exit (1);}
15.  
16.   // obtain file size:
17.   fseek (pFile , 0 , SEEK_END);
18.   lSize = ftell (pFile);
19.   rewind (pFile);
20.  
21.   // allocate memory to contain the whole file:
22.   buffer = (char*) malloc (sizeof(char)*lSize);
23.   if (buffer == NULL) {fputs ("Memory error",stderr); exit (2);}
24.  
25.   // copy the file into the buffer:
26.   result = fread (buffer,1,lSize,pFile);
27.   if (result != lSize) {fputs ("Reading error",stderr); exit (3);}
28.  
29.   /* the whole file is now loaded in the memory buffer. */
30.  
31.   // terminate
32.   fclose (pFile);
33.   free (buffer);
34.   return 0;
35. }
36.  

C Source 8

Code: C

1.   // http://www.cplusplus.com/reference/clibrary/cstdio/fseek/
2.  
3.   /* fseek example */
4.   #include <stdio.h>
5.  
6.   int main ()
7.   {
8.   FILE * pFile;
9.   pFile = fopen ( "example.txt" , "w" );
10.   fputs ( "This is an apple." , pFile );
11.   fseek ( pFile , 9 , SEEK_SET );
12.   fputs ( " sam" , pFile );
13.   fclose ( pFile );
14.   return 0;
15.   }
16.  

C Source 9

Code: C

1.   // http://www.cplusplus.com/reference/clibrary/cstdio/fgets/
2.  
3. /* fgets example */
4. #include <stdio.h>
5.  
6. int main()
7. {
8.    FILE * pFile;
9.    char mystring [100];
10.  
11.    pFile = fopen ("myfile.txt" , "r");
12.    if (pFile == NULL) perror ("Error opening file");
13.    else {
14.      fgets (mystring , 100 , pFile);
15.      puts (mystring);
16.      fclose (pFile);
17.    }
18.    return 0;
19. }
20.  

Charles

Title: Re: C Lessons
Post by: Peter on August 10, 2011, 07:49:34 AM

cool Charles,

grandmother's C  is alive !

Title: Re: C Lessons
Post by: efgee on August 10, 2011, 09:25:33 AM

Charles,
does this:

Quote

Code: (o2)

mean that these programs can be compiled with oxygen as well?

Title: Re: C Lessons
Post by: Charles Pegge on August 10, 2011, 09:38:13 AM

No, it's just a convenient code format. We don't have the standard C libraries but the syntax would be very close.

Charles

Title: Re: C Lessons
Post by: jcfuller on August 10, 2011, 10:42:22 AM

Charles,
As O2 does classes  might I  suggest that you study up on c++ too (g++) .

James

Title: Re: C Lessons
Post by: Charles Pegge on August 10, 2011, 10:52:02 AM

Certainly James,

C++ is a closer fit and gcc will do both. (In fact gcc will also do Java, Ada and  Fortran!)

Charles

Title: Re: C Lessons
Post by: Peter on August 10, 2011, 03:31:28 PM

Hi Charles,

another c-lesson  'DiskFree'

Code: [Select]

#include <windows.h>
#include <stdio.h>

int main(void)
{
 long long BytesAvailable,TotalBytesAvailable=0;
 long long capacity,TotalCapacity=0;
 long long userFree,TotalUserFree=0;
 long long used,TotalUsed=0;
 long double percent;
 int counter = 'C';
 char diskname[512];
 strcpy(diskname,"C:\\");
 printf("%-6s %15s %15s %15s %6s\n","Drive", "Capacity",
 "Available","Used","Free");

 while (counter != (1+'Z'))
 {
  diskname[0] = counter;
  if (GetDiskFreeSpaceEx(diskname, &BytesAvailable,
  &capacity,&userFree))
  {
   percent = 100.0L*(((long double)BytesAvailable)/(long
   double)capacity);
   used = capacity-BytesAvailable;
   printf("%-6s %15'lld %15'lld %15'lld %6.2Lf%%\n",
   diskname,capacity,BytesAvailable,used,percent);
   TotalBytesAvailable+=BytesAvailable;
   TotalCapacity+=capacity;
   TotalUsed+=used;
  }
  counter++;
 }

// Now print the totals
percent = 100.0L*(((long double)TotalBytesAvailable)/(long
double)TotalCapacity);
printf("\n%-6s %15'lld %15'lld %15'lld %6.2Lf%%\n", "Total:",
TotalCapacity,TotalBytesAvailable,TotalUsed,percent);
return 0;
}

Title: Re: C Lessons
Post by: JRS on August 10, 2011, 03:51:28 PM

What language was used to write the C language?  (ASM, itself, ...)

Title: Re: C Lessons
Post by: Peter on August 11, 2011, 02:59:09 AM

Hi,

The C programming language was devised in the early 1970s as a system
implementation language for the nascent Unix operating system. Derived
from the typeless language BCPL, it evolved a type structure; created
on a tiny machine as a tool to improve a meager programming
environment, it has become one of the dominant languages of today.

Title: Re: C Lessons
Post by: Charles Pegge on August 11, 2011, 04:42:31 AM

'C' was developed from 'B' but there was no 'A'. :)

Interesting how structs arrived so late in the language.

http://en.wikipedia.org/wiki/C_%28programming_language%29

Charles

Title: Re: C Lessons
Post by: Charles Pegge on August 13, 2011, 06:01:09 AM

Thanks for the DiskFree code Peter.

Function Pointer

Code: C

1.  
2.  
3.   // FUNCTION POINTER
4.  
5.   #include <stdio.h>
6.  
7.   int foo(int i,int j)
8.   {
9.     printf ("Result %i \n",i+j);
10.   }
11.  
12.   int (*pfoo)(int i,int j);
13.  
14.  
15.   int main()
16.   {
17.     pfoo=&foo;
18.     return pfoo(1,2);
19.   }
20.  

Charles

Title: Re: C Lessons
Post by: Peter on August 13, 2011, 07:28:24 AM

more pointer   :D

Code: [Select]

#include <stdio.h>

int main()
{
 int i;
 int *p;
 
 i =1;
 p =&i;
 
 printf("\nafter p = &i; is\n");
 printf(" i = %d\n",  i);
 printf(" p = %d\n",  p);
 printf("*p = %d\n", *p);
 
 *p = 2;
 
 printf("\nafter *p = 2; is\n");
 printf(" i = %d\n",  i);
 printf(" p = %d\n",  p);
 printf("*p = %d\n", *p);
 
 printf("\nsizeof(int *) = %d\n", sizeof(int *));
 
 getchar();
 return 0;
}

Title: Re: C Lessons
Post by: Peter on August 13, 2011, 07:50:35 AM

pointer and malloc

Code: [Select]

#include <stdio.h>
#include <stdlib.h>

int main()
{
 int *p;
 int n =10;
 int i;

 p = (int *) malloc(n * sizeof(int));
 if (!p)
 {
  printf("Error, not enough memory.\n);
  getchar();
  return 0;
 }

 for (i =0; i<10; i++)
  p[i] = 2*i;
 for (i =0; i<10; i++)
  printf("i = %d   p[%d] = %d\n", i, i, p[i]);
 free(p);
 
 getchar();
 return 0;
}



Title: Re: C Lessons
Post by: Peter on August 13, 2011, 08:24:01 AM

more c- lesson sinus.

Code: [Select]

#include <windows.h>
#include <stdio.h>
#include <math.h>

char text[1000];
int imax, jmax;
const double pi = 3.14159265358979323846;
double frequenz = 1.0;
int n = 100;


void Draw(HDC hdc)
{
  double x, y, dx, xmin, xmax, ymin, ymax;
  double xfaktor, yfaktor;
  int i, j, i0, j0;
 
  xmin = 0;
  xmax = 2*pi*frequenz;
  ymin = -1;
  ymax = +1;
 
  // Intervall
  dx = (xmax - xmin)/n;
 
  // Zoomfaktor
  xfaktor = imax/(xmax-xmin);
  yfaktor = jmax/(ymax-ymin);
 
  // move
  i0 = 0;
  j0 = jmax/2;
 
  MoveToEx(hdc, i0, j0, 0);
  for (x = xmin; x <= xmax + dx/2; x += dx) {
   
    // Funktion
    y = sin(x);
   
    // Pixel
    i = i0 + xfaktor * x;
    j = j0 - yfaktor * y;
   
    // lines/boxes
    LineTo(hdc, i, j);
    Rectangle(hdc, i-2, j-2, i+3, j+3);
  }
}

LRESULT CALLBACK WindowProc(HWND hwnd, UINT m, WPARAM wParam, LPARAM lParam)
{
  HDC hdc;
 
  if (m == WM_KEYDOWN) {
    if (wParam == VK_UP    && n < 5000)        n = 3*n/2;
    if (wParam == VK_DOWN  && n > 2)           n = 2*n/3;
    if (wParam == VK_LEFT  && frequenz < 1024) frequenz *= 2;
    if (wParam == VK_RIGHT && frequenz > 0.25) frequenz /= 2;
    InvalidateRect(hwnd, 0, 0);
  }
 
  else if (m == WM_PAINT) {
    hdc = GetDC(hwnd);
    Rectangle(hdc, -1, -1, imax+1, jmax+1);
    Draw(hdc);
    ReleaseDC(hwnd, hdc);
    ValidateRect(hwnd, 0);
    sprintf(text, "Sinus:  f = %.2f  n = %d", frequenz, n);
    SetWindowText(hwnd, text);
  }
 
  else if (m == WM_SIZE) {
    imax = LOWORD(lParam);
    jmax = HIWORD(lParam);
  }
  else if (m == WM_DESTROY)
    PostQuitMessage(0);
  else
    return DefWindowProc(hwnd, m, wParam, lParam);
  return 0;
}



Title: Re: C Lessons
Post by: Peter on August 13, 2011, 09:14:49 AM

lesson pow/sqrt

Code: [Select]

include "window.h"

Def Lila 0xFFC8C8

Window "Quadratic Color 2011",640,480,ws_overlapped
SetFont 16,32,0,0

single x y ax ay tx ty

While WinExit=0
For x=8 To 16
For y=1 To 420
ax= pow(x,2)
ay= pow(y,2)
tx = sqr(ax+ay)
ty = sqr(ax+ay)
Text "PETER",tx,ty,Rgb (Rand(32,255), Rand(32,255), Rand(32,255))
Next: Next
DoEvents
Wend
WinEnd
[attachment deleted by admin]

Title: Re: C Lessons
Post by: Charles Pegge on August 13, 2011, 09:17:09 AM

Thanks Peter,
I see you have to cast the p pointer when using with malloc.

Charles

Title: Re: C Lessons
Post by: JRS on August 13, 2011, 11:59:48 PM

It would be nice if a C compiler could deal with type at time of use like SB does. Declaring variables and casting is a PITA. I won't even get started on having to DIM arrays. (PITA-2)  :P

Title: Re: C Lessons
Post by: Charles Pegge on August 14, 2011, 12:35:15 AM

You can do this to some extent in C with macros, pointers and casting. Performance and flexibility are a tradeoff.

Charles

Title: Re: C Lessons
Post by: JRS on August 14, 2011, 12:46:10 AM

I really think you have to look at the application as a whole. There will be parts that most of the time the application is idle and there are parts that would benefit from a call to an extension module function written in C.

Title: Re: C Lessons
Post by: Charles Pegge on August 30, 2011, 09:03:12 PM

Bstrings and some BASIC string functions for C

Code: C

1.  
2.  
3. //=================
4. //Bstring Functions
5. //=================
6.  
7.  
8.   #include <stdio.h>
9.   #include <stdlib.h>
10.  
11.   typedef char * bstring;
12.  
13.  
14.  
15. //------------------------
16.   bstring NewString(int n)
17. //========================
18.   {
19.   int *p;
20.   p = (int*) malloc (n+6);
21.   *p = n;
22.   p++;
23.   return (char*) p;
24.   }
25.  
26.  
27.  
28. //------------------
29.   int Len(bstring s)
30. //==================
31.   {
32.   int * p=(int*) s;
33.   p--;
34.   return *p;
35.   }
36.  
37.  
38.  
39. //----------------------------------------
40.   void FillString(bstring s, int n, int c)
41. //========================================
42.   {
43.   int i;
44.   for (i=0 ; i<n ; i++)
45.   {
46.   *s = (char) c;
47.   s++;
48.   }
49.   }
50.  
51.  
52.  
53. //-------------------------
54.   bstring NullString(int n)
55. //=========================
56.   {
57.   int *p;
58.   p = (int*) malloc (n+6);
59.   *p = n;
60.   p++;
61.   FillString((bstring) p,n+2,0);
62.   return (bstring) p;
63.   }
64.  
65.  
66.  
67.  
68. //-------------------------
69.   int FreeString(bstring s)
70. //=========================
71.   {
72.   free(s-4);
73.   return 0;
74.   }
75.  
76.  
77.  
78.  
79. //------------------------------------
80.   bstring Mid(bstring s, int i, int l)
81. //====================================
82.   {
83.   bstring t;
84.   bstring u;
85.   int le;
86.   int les=Len(s);
87.   int j;
88.   if (i<0)
89.   {
90.     i=les+1+i; //offset from the right
91.   }
92.   le=l+i-1;
93.   if (le>les)
94.   {
95.    l=les-i+1;
96.   }
97.   if (l<0) l=0;
98.   t=NullString(l);
99.   if (i>les) return t;
100.   u=t;
101.   s+=i-1;
102.   for (j=0 ; j<=l ; j++) // includes boundary null
103.   {
104.     *u++ = *s++;
105.   }
106.   return t;
107.   }
108.  
109.  
110.  
111. //------------------------------
112.   bstring Left(bstring s, int i)
113. //==============================
114.   {
115.   return Mid(s,1,i);
116.   }
117.  
118.  
119.  
120. //-------------------------------
121.   bstring Right(bstring s, int i)
122. //===============================
123.   {
124.   return Mid(s,-i,Len(s));
125.   }
126.  
127.  
128.  
129.  
130. //------------------
131.   bstring Chr(int i)
132. //==================
133.   {
134.   bstring s=NewString(1);
135.   *s=(char) i;
136.   s[1]=(char) 0;
137.   return s;
138.  
139.   }
140.  
141.  
142.  
143.  
144. //--------------------------
145.   short Asc(bstring s,int i)
146. //==========================
147.   {
148.   long le=Len(s);
149.   if (i<0)
150.   {
151.    i=le+i+1; //offset from the right
152.   }
153.   if (i<1) return 0;
154.   if (i>le) return 0;
155.   i--;
156.   return (short) s[i] & 0xff;
157.  
158.   }  
159.  
160.  
161.  
162. //-----------
163.   int main ()
164. //===========
165.   {
166.   int i,n;
167.   bstring s,t;
168.  
169.   printf ("How long do you want the string? ");
170.   scanf ("%d", &i);
171.  
172.   s=NullString(i);
173.   t=NullString(i);
174.   if (s==NULL) exit (1);
175.  
176.   for (n=0; n<i; n++)
177.     s[n]=rand()%26+'a';
178.   s[i]='\0';
179.  
180.   t=Mid(s,-2,64);
181.   printf ("Random string: %s, %s, %i, %s \n",s, t, Asc(t,2), Chr(65) );
182.   FreeString (s);
183.   FreeString (t);
184.  
185.  
186.   return 0;
187.   };
188.  
189.  

Charles

Title: Re: C Lessons
Post by: Peter on August 31, 2011, 02:42:15 AM

Hi Charles,

I think the people are visiting this forum, because they are thinking that is a  Basic Forum.
And now they get a shock, if they see is much  stone age C here. It does not matter to me, I am crazy enough to write in all..
I think it will become  more and more Linux than Basic ? 

Some OxygenBasic  examples would be good  to this forum. You can get the feeling,  yes  I am here right. 

Title: Re: C Lessons
Post by: Charles Pegge on August 31, 2011, 08:21:14 AM

Hi Peter,

This dinosaur porridge will eventually become part of my Trans-platform resources. :) and it helps me appraise the possibility of a C emitter.

However I have some more Opengl geometry in the pipeline, based on the Platonic solids and their variations. I hope these will be easier to relate to.

Charles

Title: Re: C Lessons
Post by: JRS on August 31, 2011, 08:35:14 AM

I think C is the foundation of most OS and development tools we use today. Everything is a derivative of C IMHO. Linux is the future as MS waffles along trying to capture market share and caring less what effect if has on their developer base.

If this forum turns into a thinBasic like venue, then we have a problem. Only 10% of the posts there have anything to do with Basic.

Title: Re: C Lessons
Post by: Peter on August 31, 2011, 09:20:29 AM

Only 10% of the posts there have anything to do with Basic.

yes, that is correct, is more for the hobby social philosopher.  :D

Title: Re: C Lessons
Post by: Peter on August 31, 2011, 09:45:52 AM

did you know, if you learn Java, then can you talk with the Aliens!   :D

Title: Re: C Lessons
Post by: efgee on August 31, 2011, 11:01:11 AM

I really welcome Charles' exploration in C as I like to use/learn as much as I can.
(every programming language is welcome...)
This is because I haven't found THE perfect language yet.

Title: Re: C Lessons
Post by: Aurel on August 31, 2011, 11:24:06 AM

Code: [Select]

did you know, if you learn Java, then can you talk with the Aliens! :D :D :D
But hey maby you wrong - you know my uffo basicers code - it's infact some sort
of Alien language ,man.... :D :D :D

And yes ,this time i 100% agree with Pan  ;)
I know that knowlege about C is usefull ...but
And heh ...yes John is right to about thinF - to much dan babeling about
lisp and derivatives... :-\

Title: Re: C Lessons
Post by: Charles Pegge on August 03, 2012, 08:02:10 AM

GCC Windows (MinGW), Late binding, Midi Output (Tune with 2 notes :))

Code: C

1.  
2. #include <stdlib.h>
3. #include <stdio.h>
4. #include <string.h>
5. #include <math.h>
6. #include <windows.h>
7.  
8.  
9. int main()
10. {
11.   HANDLE li,ha;
12.   li=LoadLibrary("Winmm.dll");
13.   //
14.   int WINAPI (*midiOutOpen)(HANDLE*h,UINT,DWORD_PTR,DWORD_PTR,DWORD);
15.   midiOutOpen=GetProcAddress(li,"midiOutOpen");
16.   //
17.   int WINAPI (*midiOutClose)(HANDLE);
18.   midiOutClose=GetProcAddress(li,"midiOutClose");
19.   //
20.   int WINAPI (*midiOutShortMsg)(HMIDIOUT,DWORD);
21.   midiOutShortMsg=GetProcAddress(li,"midiOutShortMsg");
22.   //
23.   //FARPROC CALLBACK
24.   HANDLE        hmo;
25.   int           er;
26.   long          ch;
27.   long long     qu1,qu2,fr;
28.   //
29.   QueryPerformanceCounter( (LARGE_INTEGER*) &qu1);
30.   QueryPerformanceFrequency((LARGE_INTEGER*) &fr);
31.   fr/=1000; // for milliseconds
32.   //
33.   er=midiOutOpen(&hmo,0,0,0,0);
34.   midiOutShortMsg(hmo,0x000EC2); // instrument assign ch
35.   midiOutShortMsg(hmo,0x503791); // v n (n on)  ch
36.   Sleep(250);
37.   midiOutShortMsg(hmo,0x503781); // v n (n off) ch
38.   midiOutShortMsg(hmo,0x503191); // v n (n on)  ch
39.   Sleep(3500);
40.   midiOutShortMsg(hmo,0x503081); // v n (n off) ch
41.   //
42.   //MessageBox(0,"Hello","Greeting",0);
43.   //
44.   //scanf("%c",&ch);
45.   //
46.   QueryPerformanceCounter((LARGE_INTEGER*) &qu2);
47.   long long ti=(qu2-qu1)/fr;
48.   //printf("%i %i",ha,frd);
49.   midiOutClose(hmo);
50.   //
51.   FreeLibrary(li);
52. };
53.  

Charles