Struggling with CS50 Readability - c

Question

so I'm struggling with why I continue to get undeclared identifiers and can't seem to understand why the code isn't running properly. I'd appreciate any suggestions on how to work through this.
#include <cs50.h>
#include <ctype.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) {
int a;
int b;
int c;
string text = get_string("Text: ");
for (int i = 0; i < strlen(text); i++) {
// Count letters
a = count_letters(text);
// Count words (between spaces), words = space + 1
b = count_words(text);
// Count sentences (# of .?! in text)
c = count_sentences(text);
}
float L = a / (float)b * 100;
float S = c / (float)b * 100;
int CLI = round((0.0588 * L) - (0.296 * S) - 15.8);
if (CLI < 1) {
printf("Before Grade 1\n");
} else if (CLI > 16) {
printf("Grade 16+\n");
} else {
printf("Grade %i\n", CLI);
}
}
int count_letters(string text) {
int letters = 0;
if (text[i] > 'a' && text[i] < 'z' || text[i] > 'A' && text[i] < 'Z') {
letters++;
}
}
int count_words(string text) {
int word = 1;
if (text[i] == ' ') {
words++;
}
}
int count_sentences(string text) {
int sentence = 0;
if (text[i] == '.' || text[i] == '?' || text[i] == '!') {
sentence++;
}
}

Answer 1

I defined the symbol MISSING and implemented the functionality of cs50.h you did not share with us. You can delete all but #include <cs50.h> from that first section.
You iterate over your text in main, so you only need to operate on a single letter c in your count functions (and words is incremented if there were letters but no spaces). This was your main issue.
Moved main() to the end, so you don't need the function declarations for the count functions. Used better variable names and initialized those variables. Not sure what L, S, or CLI are. It would be a good idea to define constants for your magical values (0.0588, 0.296, 15.8).
#define MISSING
#ifndef MISSING
#include <cs50.h>
#else
#include <stdio.h>
#include <stdlib.h>
typedef char * string;
#define MAX_STR 1000
// caller frees returned string
string get_string(const char *prompt) {
char *s = malloc(MAX_STR);
if(!s) return NULL;
printf("%s", prompt);
fgets(s, MAX_STR, stdin);
return s;
}
#endif
#include <ctype.h>
#include <math.h>
#include <stdio.h>
#include <string.h>
int count_letters(char c) {
return isalpha(c);
}
int count_words(char c) {
return c == ' ';
}
int count_sentences(char c) {
return (c == '.') || (c == '?') || (c == '!');
}
int main(void) {
string text = get_string("Text: ");
int letters = 0;
int words = 0;
int sentences = 0;
for (int i = 0; i < strlen(text); i++) {
letters += count_letters(text[i]);
words += count_words(text[i]);
sentences += count_sentences(text[i]);
}
if(!words && letters) words++;
float L = 100.0 * letters / words;
float S = 100.0 * sentences / words;
int CLI = round((0.0588 * L) - (0.296 * S) - 15.8);
if (CLI < 1) {
printf("Before Grade 1\n");
} else if (CLI <= 16) {
printf("Grade %i\n", CLI);
} else {
printf("Grade 16+\n");
}
return 0;
}