Exercise 1-13 from The C Programming Language: by Brian W. Kernighan, Dennis M. Ritchie​ "Write a program to print a histogram of the lengths of words in its input. It is easy to draw the historgram with the bars horizontal; a vertical orientation is more challenging."

wordlengthhisto.c

#include <stdio.h>

//In a word or not
#define IN 1
#define OUT 0
#define MAXLENGTH 100
// Write a program to print a histogram of the lengths of words in its input. It is easy to draw the historgram with the bars horizontal; a vertical orientation is more challenging.

main(){
	//Maximum word length is 100, far more than neccesary
	int wordlengths[MAXLENGTH];
	int i,j, c, wlength,state,maxfound;

	i = j = c = wlength = maxfound = 0;
	state = OUT;

	//initialize
	for (i = 0; i < MAXLENGTH; ++i)
		wordlengths[i] = 0;

	while((c = getchar()) != EOF){
		if(c == '\n' || c == '\t' || c == ' '){
			state = OUT;
			if( wlength > 0 && wlength < MAXLENGTH ){
				if (wlength > maxfound)
					maxfound = wlength;
				wordlengths[wlength]++;
			}
			wlength = 0;
		}else{
			state = IN;
			wlength++;
		}
	}

	//Print out histogram vertically
	printf("Word Length Histogram\n");	
	for(i = 0; i < maxfound; ++i)
		printf("___");
	printf("\n");
	for(i = maxfound; i > 0; --i){
		printf("%2d",i );
		for(j=0; j <= maxfound; ++j){
			//Run through the list
			if(wordlengths[j] >= i){
				printf("|%2s","");		
			}else{
				printf("%3s","");
			}
		}
		printf("\n");
	}
	for(i =0; i <= maxfound; ++i){
		if(i <= 10){
			printf("%2s%d","",i);	
		}else{
			printf("%3d",i);
		}
	}
		
	printf("\n");
	for(i = 0; i < maxfound; ++i)
		printf("___");
	printf("\n");	

}

To run:

$cc wordlengthhisto.c
$./a.out < somefile.txt

Thanks!