readability.c

#include <cs50.h>
#include <stdio.h>
#include <string.h>
#include <math.h>

int count_sentences(string text);
int count_words(string text);
int count_letters(string text);

int main(void)
{
    string text = get_string("Text: ");

    // get infos from text for calculating Coleman-Liau index
    int sentence_count = count_sentences(text);
    int word_count = count_words(text);
    int letter_count = count_letters(text);

    // calculate Coleman-Liau index
    float L = ((float)letter_count / (float)word_count) * 100.0;
    float S = ((float)sentence_count / (float)word_count) * 100.0;
    int index = (int)(round(0.0588 * L - 0.296 * S - 15.8));

    // check index and print result accordingly
    // U.S. Grade system has only 1-16
    if (index < 0)
    {
        printf("Before Grade 1");
    }
    else if (index >= 16)
    {
        printf("Grade 16+");
    }
    else
    {
        printf("Grade %d", index);
    }

    printf("\n");
}

int count_sentences(string text)
{
    int sentence_count = 0;

    for (int i = 0; i < strlen(text); i++)
    {
        // '.', '!', '?' are sentence ending indicators
        if (text[i] == '.' || text[i] == '!' || text[i] == '?')
        {
            sentence_count++;
        }
    }

    return sentence_count;
}

int count_words(string text)
{
    // starts with 1 word since it counts ' '
    // so if the input is "Congrats!"
    // there is no space but still count as 1 word
    // and assume that input always have atleast 1 word
    int word_count = 1;

    for (int i = 0; i < strlen(text); i++)
    {
        // assumes no multiple consecutive spaces
        // assumes no spaces at the start or the end of text
        if (text[i] == ' ')
        {
            word_count++;
        }
    }

    return word_count;
}

int count_letters(string text)
{
    int letter_count = 0;

    for (int i = 0; i < strlen(text); i++)
    {
        // count only if within 'a-z' or 'A-Z' ASCII range
        if ((text[i] >= 'a' && text[i] <= 'z') || (text[i] >= 'A' && text[i] <= 'Z'))
        {
            letter_count++;
        }
    }

    return letter_count;
}