In this program, I need to find the reading grade level of a text inputted by the user.

The number of letters, words and sentences seem to be correct but theindex is coimg out wrong.

The assumptions given in the question:
a sentence:
will contain at least one word;
will not start or end with a space; and
will not have multiple spaces in a row.

Here is the code I wrote:

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

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

int main(void)
{
    // Prompt the user for some text
    string text = get_string("Text: ");

    // Count the number of letters, words, and sentences in the text
    float letters = count_letters(text);
    float words = count_words(text);
    float sentences = count_sentences(text);

    // Compute the Coleman-Liau index
    float L = (letters/words)*100;
    float S = (sentences/words)*100;
    float index = 0.0588 * L - 0.296 * S - 15.8;
    int rounded_index = round(index);

    printf("%fn", letters);
    printf("%fn", words);
    printf("%fn", sentences);
    printf("%fn", L);
    printf("%fn", S);
    printf("%fn", index);

    // Print the grade level
    if (rounded_index<1)
        printf("Before Grade 1n");
    else if (rounded_index>=1 && rounded_index<16)
        printf("Grade %in", rounded_index);
    else
        printf("Grade 16+n");
}

int count_letters(string text)
{
    int lettercount = 0;
    for (int i=0, length = strlen(text); i<length; i++)
    {
        if (isalpha(text[i])!=0)
        {
            lettercount++;
        }
    }
    return lettercount;
}

int count_words(string text)
{
    int wordcount = 1;
    for (int i=0, length = strlen(text); i<length; i++)
    {
        if (text[i]==' ')
            wordcount++;
    }
}
    return wordcount;
}

int count_sentences(string text)
{
   int sentencecount = 0;
   for (int i=0, length = strlen(text); i<length; i++)
   {
        if (text[i]=='.' || text[i]=='?' || text[i]=='!')
        {
            sentencecount++;
        }
   }
   return sentencecount;
}