Generates a chart of MIDI notes and associated frequencies

midi_to_freq_chart.c

/* MIDI to Frequency Chart
 * Jacob Joaquin <jacobjoaquin@gmail.com>
 * csoundblog.com
 *
 * Based on Listing 1.2 of The Audio Programming Book
 * Edited by Richard Boulanger and Victor Lazzarini
 * Chapter 1 - Programming in C
 * Richard Dobson
 */
  
#include <math.h>
#include <stdio.h>
#include <string.h>

double midi_to_hz(int midi_note);
void midi_to_note_octave(int midi_note, char* string);

int main()
{
    int i;
    char note_octave[5];
    
    for (i = 0; i <= 127; i++)
    {
        midi_to_note_octave(i, note_octave);
        printf("%d\t%s\t%f\n", i, note_octave, midi_to_hz(i));
    }
        
    return 0;
}

double midi_to_hz(int midi_note)
{
    static const double half_step = 1.0594630943592953;  
    static const double midi_c0 = 8.175798915643707;
    
    return midi_c0 * pow(half_step, midi_note);
}

void midi_to_note_octave(int midi_note, char* string)
{
    static const char* notes[] = {"c", "c#", "d", "d#", "e", "f", "f#", "g",
                                  "g#", "a", "a#", "b"};    
    static const int tet_12 = 12;
    char buffer[3];
    
    strcpy(string, notes[midi_note % tet_12]);
    sprintf(buffer, "%d", midi_note / tet_12);
    strcat(string, buffer);
}