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

#define MAXSTRLEN (81)
#define MAXMARKS  (60)

char *reverse(char *a);
char *stripCR(char *s);

int main(int argc, char *argv[])
{
	char filename[MAXSTRLEN];
	long int count[256];
	int i, j;
	FILE *fp;
	long int max, bytes;
	int marks;
	double marksize;

	// Check for file name on command line, get from user if not found
	if(argc < 2)
	{
		printf("Enter filename: ");
		fgets(filename, MAXSTRLEN, stdin);
		stripCR(filename);
	}
	else
	{
		strncpy(filename, argv[1], MAXSTRLEN);
	}

	// Open file for reading (in binary mode)
	printf("Attempting to open file: <%s>\n", filename);

	fp = fopen(filename, "rb");

	if(NULL == fp)
	{
		printf("Failed to open file for reading - abort!\n");
		return(1);
	}

	// Initialize count variables
	for(i = 0; i < 256; i++)
		count[i] = 0;

	bytes = 0;

	// count values in file
	while(!feof(fp))
	{
		count[fgetc(fp)]++;
		bytes++;
	}

	// Find most frequent value
	for(max = 0, i = 0; i < 256; i++)
		if(count[i] > max)
			max = count[i];

	// determine the scale factor for the histogram bars
	marksize = (double) MAXMARKS / (double) max;

	// Output histogram
	for(i = 0; i < 256; i++)
	{
		printf("%03i: <% 8li> ", i, count[i]);
		marks = (int) (count[i] * marksize);
		for(j = 0; j < MAXMARKS; j++)
			printf("%c", (j < marks)? '*' : ' ');
		printf("\n");
	}

	// Ouptut summary info
	printf("\nTotal bytes = %li\n", bytes);

	return(0);
}

char *stripCR(char *s)
{
	char *a;

	a = s;

	do
	{
		switch(*a)
		{
			case '\n':
			case '\f':
				*a = '\0';
		}
	} while('\0' != *(a++));

	return(s);
}