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Brace Block

  do {
     ...
  } while(0)

This may seem non-sensical, as the while loop never loops. It just
gets executed once only. 

However you can use 'break' anywhere in the block to jump to 'escape' to the
end of the block.


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Program Name (real, not given)

Get argv[0] from the environment (The real file name used not the given name)
    extern char **environ;  /* save as in main(ac,av,ep) */
    printf("i am %s\n", environ[-2]);
                                 --- Tom Christiansen <tchrist@convex.COM>

environ[-2] may be argv[argc - 1], not necessary equal to argv[0].
If you throw in some more nonportable assumptions about argc, integers,
and pointers, I'd suggest:
        char ** argv()
        {
                extern char **  environ;
                int             ac = 1;

                while ((int)environ[ -2 - ac ] != ac) ac++; 
                return environ - (1 + ac);
        }
(I have also seen a compiler provide an `extern char ** __Argv', once.)
                                  --- Jutta Degner <jutta@opal.cs.tu-berlin.de>

On (system V Rev 4) you can ask the operation system.
    #include <sys/types.h>
    #include <sys/procfs.h>
    #include <fcntl.h>

    char *cmd_name() {
        char fn[12];
        static fd = -1;
        static prpsinfo_t pr;

        if (fd == -1) {
            sprintf(fn, "/proc/%05d", getpid());
            if ((fd = open(fn, O_RDONLY)) == -1) {
                perror(fn); exit(1);
            }
            if (ioctl(fd, PIOCPSINFO, (void *)&pr) == -1) {
                perror("ioctl(PIOCPSINFO)"); exit(1);
            }
        }
        return pr.pr_fname;
    }

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Argc[0] modification for ps output
    write individual characters into argv[0][0..n]
    but if my new name is longer than the old name, your stuck

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convert "Sun Sep 16 01:03:52 1973" into a time_t

   You can use the 'getdate.y' file from many packages, like 'cnews'. Just
'yacc' it, get the resulting .c file and try it on your compiler..

                                   --- Michel Pollet  michel@trantor.uucp
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Multiple peak detection

Find distinct peaks in an array of data.


Param: delta (defines kind of a tolerance and depends on your data)
min = Inf (or some very high value)
max = -Inf (or some very low value)
lookformax = 1
for every datapoint d [0..maxdata] in array arr do
  this =  arr[d]
  if this > max
    max = this
    maxpos = d
  endif
  if this < min
    min = this
    minpos = d
  endif

  if lookformax == 1
    if this < max-delta
      there's a maximum at position maxpos
      min = this
      minpos = d
      lookformax = 0
    endif
  else
    if this > min+delta
      there's a minimum at position minpos
      max = this
      maxpos = d
      lookformax = 1
    endif
  endif

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