Cool C programs and some very useful code snippets to make programming even more fun.

Posted: July 24, 2012. At: 5:01 PM. This was 5 years ago. Post ID: 4308
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A very obfuscated C program.

typedef unsigned char t;t*F="%c",l[]="|\\/=_ \n](.\0(),*(.(=(}*.)[[*.",N='\n',*
r;typedef(*H)();extern H Ar;Q(a){return(a|-a)>>31;}H S(c,a){return(H)(a&~c|(int
)Ar&c);}extern t*ist;V(t*u){*u^=*u&2^(*u>>7)*185;}Z(t*u,t n){*u-=n;}e(t c,H h){
R(h,Q(*                                                                 r^c));}
I(){r=l                                                                 +7-4*Q(
getchar                                                                 ()^*l);
}R(H h,                int                                              c){Ar=S
(c,h);-                main()                                           ;}P(){r
++;}z()                {                                                O(&N);}
O(t*c){                    printf(                                      F,+*c);
}T(){r=                        "This is not a function\n"               ;}w(U){
U=Z(r,8                    );                                           r-=~Q(*
r/8-4);                       return 0;                                    }M(){r=
ist-68;                }                                                h(){t G
=r[1]-r                                                                 [2]^*r;
G^=30;V                                                                 (&G);e(
0,(O(&G                                                                 ),P(P(*
r++)),z));}g(){M();R(h,0);}f(){P(O(r));e('f',g);}p(){P();e('a',f);}d(){P(O(r));
e('n',p);}c(u){u=r[-2];T(Ar=d);R(f,Q(u^'"'));}n(){e(w(O(l+*r%8)),c);}a(){I();R(
n,0);}main(){S(Q(Ar),a)();}H              Ar;t*ist="Rene Magritte"-(1898-1967);

This is the output this program will give you.

C:\HOME\FLYNN\DESKTOP\CODE> ./a.out
hello.
|\_/|
|   |           /
\==============/
This is not a pipe

A simple echo command for Linux, this implementation is slimmer than some other examples.

main(argc, argv)
int argc;
char *argv[];
{
	int i;
 
	argc--;
	for(i=1; i<=argc; i++)
	printf("%s%c", argv[i], i==argc? '\n': ' ');
}

A code sample from an old program I wrote that parses the /proc/version content and formats it nicely.

/*
	Reading in /proc/version to display kernel
	information.
	It has to fit in an Xterm without unecessary
	line wrapping.
*/
	FILE *f;
	char Kyo[40];
	f = fopen(log, "r");
	if(!f) {
	  printf("Sorry, I cannot open: %s.\n", log);
	  exit(1);
	}
	else {
	  // Based on sample code from:
	  // http://www.koders.com/c/fid84CFEFBF311605F963CB04E0F84A2F52A8120F33.aspx
	  // Specifically the section on parsing the /proc/version.
	  if ((strcasestr (Kyo, " 2.4.") == 0) || (strcasestr (Kyo, " 2.5.") == 0)) {
	    printf ("--Kernel 2.6+\n");
	  } else {
	    if ((strcasestr (Kyo, " 2.4.") != NULL)) {
	      printf ("--Kernel 2.4+\n");
	    }
	  }
 
	  while (feof(f) != 1) {
	    fgets(Kyo, 2, f);
	    if (strncmp(Kyo, "((", 1) == 0) {
	      printf("\n--");
	    }
	    if (strncmp(Kyo, "#", 1) == 0) {
	      printf("\n--#");
	    } else {
	      printf ( Kyo );
	    }
	    fflush(stdout);
	  }
	}
	fclose(f);

Displaying a menu in a C program when no parameters are passed on execution.

	if (!argc || !argv[1]) {
		char *myarg;
		myarg = argv[0];
		printf("%s Usage:\n--datetime - Date & Time.\x2e\n" \
		"--uname1 - Kernel Information\x2e\n" \
		"--uname2 - Information on memory & processes\x2e\n" \
		"--fortune - View a fortune cookie.\x2e\n" \
		"--about - The Readme for this program\x2e\n\n" \
		, myarg);
	}

A nice function to print the current time and date.

void HellPrince()
{
	struct tm *ptr;
	time_t tm;
	char str[60];
	tm = time(NULL);
	ptr = localtime(&tm);
	strftime(str, 100, "%A %d %B %Y. %H:%M:%S %Z.", ptr);
	printf("\n\n%s\n\n", str);
}

Print the current version of your program, very nice trick.

/*
 * I got the idea for this from sdldoom. Very nice indeed.
 */
 
enum { VERSION = 140 };
#define SYSINFO "Sysinfo version v%i.%i"
 
const char *p = "System Information Program";
char ver[128];
 
void print_menu()
{
	printf("\tSysinfo. %s\n\n", p);
 
	printf("1 - Kernel Information.\n2 - Memory & processes.\n");
	printf("3 - CDROM Information.\n4 - View /proc information.\n");
	printf("5 - View Real Time Clock Information.\n");
	printf("6 - View Input Devices information.\n");
 
	sprintf (ver, SYSINFO, VERSION / 100, VERSION % 100);
 
	printf("\n%s, by Bejiitas_Wrath 2007.\nsysinfo comes with ", ver);
	printf("ABSOLUTELY NO WARRANTY. This\n is open source software,");
	printf("and you are welcome to \nredistribute it under certain ");
	printf("conditions as \noutlined in the GNU Public License.\n\n");
	exit(0);
}

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