C Lessons

[Charles Pegge]

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

Charles

[JRS]

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) 

[Charles Pegge]

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

Charles

[JRS]

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.

[Charles Pegge]

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

[Peter]

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. 

[Charles Pegge]

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

[JRS]

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.

[Peter]

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

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

[Peter]

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

[efgee]

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.

[Aurel]

Code: [Select]

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

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...

[Charles Pegge]

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