Messy, as it's not the final draft

helpers.c

// Helper functions for music

#include <cs50.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <math.h>
#include "helpers.h"

int duration(string fraction)
{
    int nom;
    int denom;
    int eights;
    switch(fraction[0]){
        case '1':
            nom = 1;
            // printf("non reassinged: %i\n", nom);
        break;
        case '2':
            nom = 2;
            // printf("non reassinged: %i\n", nom);
        break;
        case '3':
            nom = 3;
            // printf("non reassinged: %i\n", nom);
        break;
        case '4':
            nom = 4;
            // printf("non reassinged: %i\n", nom);
        break;
        case '5':
            nom = 5;
            // printf("non reassinged: %i\n", nom);
        break;
        case '6':
            nom = 6;
            // printf("non reassinged: %i\n", nom);
        break;
        case '7':
            nom = 7;
            // printf("non reassinged: %i\n", nom);
        break;
        case '8':
            nom = 8;
            // printf("non reassinged: %i\n", nom);
        break;

    }

    switch(fraction[2]){
        case '1':
            denom = 1;
            // printf("whole");
            // return 8;
        break;
        case '2':
            denom = 2;
        // printf("half");
            // return 4;
        break;
        case '4':
            denom = 4;
        // printf("denom quarter %i\n", denom);
            // return 2;
        break;
        case '8':
            denom = 8;
        // printf("denom eighth %i\n", denom);
            // return 1;
        break;

    }
    switch(denom){
        case 1:
            eights = 8;
            // printf("eights: %i\n", eights);
        break;
        case 2:
            eights = nom * 4;
            // printf("eights: %i\n", eights);
        break;
        case 4:
            eights = nom * 2;
            // printf("eights: %i\n", eights);
        break;
        case 8:
            eights = nom * 1;
            // printf("eights: %i\n", eights);
        break;
    }

    // printf("nom/denom %i\n ", (nom +denom) );
    return eights;
}

// // Calculates frequency (in Hz) of a note
int frequency(string note)
{
    int letter;
    int octave = 0;
    float semitone = 0;
    int initfreq = 440.0;
    float freq = 0;
    // bool double_sharp = false;
    // bool double_flat = false;
    bool sharp = false;
    bool flat = false;

    for(int i = 0;i < strlen(note); i++){
        if(note[i] == 'b'){
            flat = true;
        } else if((isalpha(note[i])) && (note[i] != 'b')){
            letter = note[i];
        } else if(note[i] == '#'){
            sharp = true;
        } else if(isdigit(note[i])){
            octave = note[i];
        } else {
            printf("%c is not valid", note[i]);
            return 1;
        }
    }

    // printf("%c\n%c\n", letter, octave);
    // // printf("sharp: %s", sharp ? "true" : "false");
    // printf("flat: %s", flat ? "true" : "false");

// attempt to use function
    // getter(letter,sharp, flat,initfreq,semitone,freq);
        // int getter(int letter bool sharp bool flat int initfreq int semitone){


    switch(letter){
        case 'A':
            if(flat == true){
                semitone = -1.0;
            } else if(sharp){
                semitone = 1.0;
            } else {
                semitone = 0;
            }
        break;
        case 'B':
            if(flat == true){
                semitone = 1.0;
            } else if(sharp){
                semitone = 3.0;
            } else {
                semitone = 2.0;
            }
        break;
        case 'C':
            if(flat == true){
                semitone = -10.0;
            } else if(sharp){
                semitone = -8.0;
            } else {
                semitone = -9.0;
            }
        break;
        case 'D':
            if(flat == true){
                semitone = -8.0;
            } else if(sharp){
                semitone = -6.0;
            } else {
                semitone = -7.0;
            }
        break;
        case 'E':
            if(flat == true){
                semitone = -6.0;
            } else if(sharp){
                semitone = -4.0;
            } else {
                semitone = -5.0;
            }
        break;
        case 'F':
            if(flat == true){
                semitone = -5.0;
            } else if(sharp){
                semitone = -3.0;
            } else {
                semitone = -4.0;
            }
        break;
        case 'G':
            if(flat == true){
                semitone = -3.0;
            } else if(sharp){
                semitone = -1.0;
            } else {
                semitone = -2.0;
            }
        break;
    }
    // print semitone
    // printf("semitones: %f\n", semitone);
    // printf("octave: %c\n", octave);


    // get frequency
    // printf("no octave:%i\n", freq);

        // if(letter == 'A'){
        //       ///440
        //     if(sharp == true){
        //         freq = round(initfreq * pow(2.0, 1.0/12));
        //     } else if(flat == true){
        //         freq = round(initfreq / pow(2.0, 1.0/12));
        //     } else{
        //         freq = initfreq;
        //     }
        // } else if(letter != 'A') {
        //     // B
        // }
    freq = initfreq * pow(2.0, semitone/12.0);

    switch(octave){

        case '1':
            freq = ((freq / 2.0) / 2.0) / 2.0;
        break;
        case '2':
            freq = (freq / 2.0) / 2.0;
        break;
        case '3':
            freq = freq / 2.0;
        break;
        case '4':
            freq = freq * 1;
        break;
        case '5':
            freq = freq * 2.0;
        break;
        case '6':
            freq = (freq * 2.0) * 2.0;
        break;
        case '7':
            freq = ((freq * 2.0) * 2.0) * 2.0;
        break;
    }
    // printf("%i", freq);
    freq = round(freq);
    return freq;

}

// Determines whether a string represents a rest
bool is_rest(string s)
{
    // s = get_string("Input: ");
    // not a rest
    if(s[0] != '\0'){
        // printf("false");
        return false;
    } else {
        // a rest
        // printf("true");
        return true;
    }
    return false;
}