Testchar

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

int
main ()
{
  int cnt = 0;
  char *cols[43];
  size_t n = 0;
  FILE *fp = fopen ("input.txt", "r");
  FILE *fp2= fopen ("output.txt", "a");
  if (fp == NULL )
    {
      perror ("Unable to open file!");
      exit (1);
    }
  char *line2 = NULL;
  size_t len = 0;
clock_t begin = clock();

/* here, do your time-consuming job */

  while (getline (&line2, &len, fp) != -1)
    {
      n = 0;
      if (len > 43)
    for (char *p = strtok (line2, ";"); p; p = strtok (NULL, ";"))
      {
        if (n < 4)
          fprintf (fp2,"%s;", p);
        else if (n > 3 && n < 42)
          {
        for (int x = n - 1; x > 2; x--)
          {
            if (strcmp (cols[x], p) == 0)
              break;
            else if (x < 4)
              fprintf (fp2,"%s", p);
          }
        fprintf (fp2,";");
          }
        cols[n++] = p;
        if (n > 42)
          break;
      }
      fprintf (fp2,"\n");
    }

clock_t end = clock();
double time_spent = (double)(end - begin) / CLOCKS_PER_SEC;
printf ("%f\n",time_spent);
  return 0;
}