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	Category-0 solutions to The C Programming Language, 2nd Edition	zlg

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path: root/ch2/2-06_setbits.c (follow)

Age	Commit message (Collapse)	Author	Files	Lines
2013-03-31	Solve Exercise 2-6: setbits()	zlg	1	-0/+44

Copyleft 2009-2024 ZLG. Powered by cgit.

#include <stdio.h>

/* The C Programming Language: 2nd Edition
 *
 * Exercise 1-13: Write a program to print a histogram of the lengths of words
 * in its input. It is easy to draw the histogram with the bars horizontal; a
 * vertical orientation is more challenging.
 *
 * Answer: Keep an array of lengths that you can add to when you come out of a
 * word. At the end of input, you'll have your collection of data. The rest is
 * deciding how you want to display it. I chose a horizontal layout for this
 * exercise.
 *
 * To do the vertical, you need to choose a theoretical maximum (80 is probably
 * a bit too high) and simply iterate over the data set checking for the word
 * length that has that frequency or lower.
 *
 * TODO: Write the vertical histogram code.
 */

#define IN 1
#define OUT 0
#define MINWLENGTH 2
#define MAXWLENGTH 20

int main(void) {
	/* Rundown of variables:
	 * i, j = reusable placeholder variables
	 * state = inside or outside a word
	 * ltrs = letter count
	 * wrds = word count
	 * lines = you should be shot if you don't know
	 * lengths = an array that keeps track of how often words up to x chars long
	 *           occur.
	 */
	int state, ltrs, wrds, lines, wlen, i, j;
	int lengths[MAXWLENGTH];
	for (i = 0; i <= MAXWLENGTH; ++i) {
		lengths[i] = 0;
	}
	ltrs = wrds = wlen = 0;
	lines = 1;
	state = OUT;
	/* Capture input until it ends */
	while ((i = getchar()) != EOF) {
		/* If it's whitespace, we've exited a word */
		if (i == '\n' || i == ' ' || i == '\t') {
			if (state == IN) {
				++wrds; // ...and should increase the count.
				state = OUT;
				/* Check to see if the word is eligible to be counted. */
				if (wlen <= MAXWLENGTH) {
					++lengths[wlen];
				}
				/* Reset our word length now. */
				wlen = 0;
			}
			/* If it's a new line, we're still out of a word but need to increment the
			   line count */
			if (i == '\n') {
				++lines;
			}
		} else {
			/* If nothing else, we know it's just a random character or a letter. */
			state = IN;
			++wlen;
		}
		/* Everything that's input counts as a letter. */
		++ltrs;
	}
	printf("\nWORD LENGTH FREQUENCY\n     ");
	for (i = 5; i < 80; i += 5) {
		printf("   %2d", i);
	}
	/* End the chart heading. */
	printf("\n");
	j = MINWLENGTH;
	while (j <= MAXWLENGTH) {
		i = lengths[j];
		if (i > 0) {
			printf("%2d | ", j);
			while (i > 0) {
				printf("#");
				i = i - 1;
			}
			printf("\n");
		}
		++j;
	}
	printf("%d words, %d chars, %d lines.\n", wrds, ltrs, lines);
	return 0;
}