charcount.c - prints histogram of frequencies of different characters in input (only printing visible ones)

charcount.c

#include <stdio.h>

/*
    Author: Matias Lago
    Objective: Print histogram of frequencies of different characters in input (will only print visible ones)
*/

#define STARTING_CHARACTER ' '
#define ENDING_CHARACTER '~'

int main() 
{
    int c;
    int characters[(ENDING_CHARACTER - STARTING_CHARACTER) + 1];

    for(int i=STARTING_CHARACTER; i <= ENDING_CHARACTER; ++i)
        characters[i - STARTING_CHARACTER] = 0;

    while((c = getchar()) != EOF) { 
        ++characters[c - STARTING_CHARACTER];
    }

    for(int i=STARTING_CHARACTER; i <= ENDING_CHARACTER; ++i) {
        printf("%d (%c): ", i, i);
        for(int j=0; j < characters[i - STARTING_CHARACTER]; ++j)
            putchar('-');
        putchar('\n');
    }
}

Works well when:

• Same starting and ending character
• No input
• Ending Character > Starting Character (negative array size error)
• Adapts well to specific Ranges (i.e digits only, uppercase only, etc)