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/****************************************************************/
/* */
/* Collect file statistics */
/* */
/* Public domain demo program for analyzing encrypted */
/* files. By: Bob Stout */
/* */
/****************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <assert.h>
main(int argc, char *argv[])
{
int i, ch, hist = 0;
long n = 0L;
double mean = 0., stdev = 0., ftmp;
static unsigned bins[256];
FILE *infile;
assert(infile = fopen(argv[1], "rb"));
while (!feof(infile))
{
if (EOF == (ch = fgetc(infile)))
break;
bins[ch] += 1;
++n;
}
fclose(infile);
for (i = 0; i < 256; ++i)
{
mean += (double)(bins[i]);
if (bins[i])
++hist;
}
mean /= 256.;
for (i = 0; i < 256; ++i)
{
ftmp = (double)(bins[i]) - mean;
stdev += (ftmp * ftmp);
}
ftmp = stdev / 255.;
stdev = sqrt(ftmp);
printf("%ld Characters were read from %s\n"
"There are an average of %f occurances of each character\n"
"%d Characters out of 256 possible were used\n"
"The standard deviation is %f\n"
"The coefficient of variation is %f%%\n",
n, argv[1], mean, hist, stdev, (100. * stdev) / mean);
return EXIT_SUCCESS;
}
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