Need this to play music - c++

Question

Game dev class. Trying to understand what i did wrong here. Did I add the wrong thing, or do i have it at the wrong place.
my goal was to add music.
#include "allegro5/allegro.h"
#include <allegro5/allegro_image.h>
#include <allegro5/allegro_font.h>
#include <allegro5/allegro_ttf.h>
#include <allegro5/allegro_native_dialog.h>
#include <stdio.h>
#include <string>
#include <allegro5\allegro_audio.h>
#include <allegro5\allegro_acodec.h>
#define FPS 60
#define SCREEN_WIDTH 800
#define SCREEN_HEIGHT 600
#define BLACK al_map_rgb(0, 0, 0)
#define WHITE al_map_rgb(255, 255, 255)
//Prototypes
bool initializeAllegro();
//Essential Allegro pointers
ALLEGRO_DISPLAY *display = NULL;
ALLEGRO_EVENT_QUEUE *eventQueue = NULL;
ALLEGRO_TIMER *timer = NULL;
ALLEGRO_FONT *arial14;
int main()
{
ALLEGRO_BITMAP *backgroundImage; //Bitmap for the background image(star field)
int backgroundImageWidth = 0, backgroundImageHeight = 0;
bool redrawRequired = true;
//Using std:string for name, so length is not a factor
std::string userName = "";
std::string prompt1 = "Enter your Player's name below";
std::string prompt2 = "(Letters & digits only. Backspace to erase.)";
std::string prompt3 = "Press Enter to accept...";
std::string prompt4 = "Press Escape to exit...";
char keyToAdd = ' ';
bool enteringUserName = true;
bool quit = false;
//Initialize allegro, etc
if (!initializeAllegro()) return -1;
//load the arial font
arial14 = al_load_font("arial-mt-black.ttf", 14, 0);
if (!arial14)
{
return -3;
}
//test running music
al_init_acodec_addon();
ALLEGRO_SAMPLE *song = al_load_sample("hideandseek.wav");
ALLEGRO_SAMPLE_INSTANCE *songInstance = al_create_sample_instance(song);
al_set_sample_instance_playmode(songInstance, ALLEGRO_PLAYMODE_LOOP);
al_attach_sample_instance_to_mixer(songInstance, al_get_default_mixer());
//Load the background picture
if (!(backgroundImage = al_load_bitmap("starbackground.bmp")))
{
return -5;
}
//Get dimensions of the background image
backgroundImageWidth = al_get_bitmap_width(backgroundImage);
backgroundImageHeight = al_get_bitmap_height(backgroundImage);
//Set the back buffer as the drawing bitmap for the display
al_set_target_bitmap(al_get_backbuffer(display));
//Initialize the event queue
eventQueue = al_create_event_queue();
if (!eventQueue)
{
al_destroy_display(display);
al_destroy_timer(timer);
return -1;
}
//Register events as arriving from these sources: display, timer, keyboard
al_register_event_source(eventQueue, al_get_display_event_source(display));
al_register_event_source(eventQueue, al_get_timer_event_source(timer));
al_register_event_source(eventQueue, al_get_keyboard_event_source());
al_flip_display();
//play song
al_play_sample_instance(songInstance);
//Start up the timer. Don't do this until just before the game is to start!
al_start_timer(timer);
//This would be a loop solely for entering the user's name, not starting the game
//Allegro keycodes are laid out as follows. (Full set of key codes is included in keycodes.h)
//Key codes for capital letters are 1 - 26 for A - Z
//Digit values are 27 - 36 for the top digits (0 - 9), and 37 - 46 for the keypad
while (!quit)
{
ALLEGRO_EVENT evt;
//Wait for one of the allegro-defined events
al_wait_for_event(eventQueue, &evt);
//An event was generated. Check for all possible event types
switch (evt.type)
{
case ALLEGRO_EVENT_KEY_CHAR:
if (evt.keyboard.keycode >= 1 && evt.keyboard.keycode <= 26) //It's a capital letter
{
//Convert to ASCII capital
keyToAdd = *al_keycode_to_name(evt.keyboard.keycode);
userName += keyToAdd;
}
else if (evt.keyboard.keycode >= 27 && evt.keyboard.keycode <= 36)
{
//Convert to digit
keyToAdd = evt.keyboard.keycode + 21;
userName += keyToAdd;
}
//Handle digits on keypad
else if (evt.keyboard.keycode >= 37 && evt.keyboard.keycode <= 46)
{
//Convert to digit
keyToAdd = evt.keyboard.keycode + 11;
userName += keyToAdd;
}
else //Handle a few other keys
{
switch(evt.keyboard.keycode)
{
case ALLEGRO_KEY_BACKSPACE:
if (userName.length() > 0)
userName = userName.substr(0, userName.length() - 1);
break;
//Enter key stops username entry
case ALLEGRO_KEY_ENTER:
case ALLEGRO_KEY_PAD_ENTER:
enteringUserName = false;
break;
case ALLEGRO_KEY_ESCAPE:
quit = true;
break;
}
}
break;
case ALLEGRO_EVENT_DISPLAY_CLOSE:
quit = true;
break;
case ALLEGRO_EVENT_TIMER:
redrawRequired = true;
break;
}//END switch evt.type
//Rerender the entire scene
if (redrawRequired && al_is_event_queue_empty(eventQueue))
{
redrawRequired = false;
al_clear_to_color(BLACK); //Just in case
//Draw background
al_draw_scaled_bitmap(backgroundImage, 0, 0, backgroundImageWidth, backgroundImageHeight,
0, 0, SCREEN_WIDTH, SCREEN_HEIGHT, 0);
//Prompt for name to be entered
al_draw_textf (arial14, WHITE, 0, 30, 0, "%s", prompt1.c_str());
al_draw_textf (arial14, WHITE, 0, 50, 0, "%s", prompt2.c_str());
if (userName.length() > 0)
{
if (enteringUserName)
{
al_draw_textf (arial14, WHITE, 0, 70, 0, "%s", userName.c_str());
al_draw_textf (arial14, WHITE, 0, 90, 0, "%s", prompt3.c_str());
}
else
{
al_draw_textf (arial14, WHITE, 0, 70, 0, "You entered your name as-->%s", userName.c_str());
}
}
al_draw_textf(arial14, WHITE, 0, 400, 0, "%s", prompt4.c_str());
al_flip_display();
}//END rendering the screen
}//END input Loop
//Release all dynamically allocated memory
al_destroy_bitmap(backgroundImage);
al_destroy_font(arial14);
al_destroy_timer(timer);
al_destroy_display(display);
al_destroy_event_queue(eventQueue);
//destroy songs
al_destroy_sample(song);
al_destroy_sample_instance(songInstance);
return 0;
}//END main
//Take care of Allegro initialization tasks
//Return false if any fail.
bool initializeAllegro()
{
bool success = true;
//Init basic environment
if (!al_init())
{
al_show_native_message_box(NULL, "ERROR", "Allegro failed to initialize!", NULL, NULL, NULL);
success = false;
}
//Initialize keyboard input
if (!al_install_keyboard())
{
al_show_native_message_box(NULL, "ERROR", "Keyboard failed to initialize!", NULL, NULL, NULL);
success = false;
}
//Initialize timer
timer = al_create_timer(1.0 / FPS);
if (!timer)
{
al_show_native_message_box(NULL, "ERROR", "Timer failed to initialize!", NULL, NULL, NULL);
success = false;
}
//Initialize display
display = al_create_display(SCREEN_WIDTH, SCREEN_HEIGHT);
if (!display)
{
al_show_native_message_box(NULL, "ERROR", "Display failed to initialize!", NULL, NULL, NULL);
success = false;
}
//Initialize the image mechanism
if (!al_init_image_addon())
{
al_show_native_message_box(NULL, "ERROR", "Image addon failed to initialize!", NULL, NULL, NULL);
success = false;
}
al_init_font_addon();
al_init_ttf_addon();
return success;
}//END initializeAllegro
Any wav file should work.
i get the error message -
First-chance exception at 0x0F196486
(allegro-5.0.10-monolith-md-debug.dll) in User Input Project.exe:
0xC0000005: Access violation reading location 0x00000000. Unhandled
exception at 0x0F196486 (allegro-5.0.10-monolith-md-debug.dll) in User
Input Project.exe: 0xC0000005: Access violation reading location
0x00000000.
The program '[9596] User Input Project.exe' has exited with code 0
(0x0).

Answer 1

I mentioned to step through things with a debugger in my comment, but the code smell here is this:
ALLEGRO_SAMPLE *song = al_load_sample("hideandseek.wav");
ALLEGRO_SAMPLE_INSTANCE *songInstance = al_create_sample_instance(song);
You should Definitely be checking for (song == NULL) before you call al_create_sample_instance()
If your path to the .WAV file is wrong or if the loading fails for any other reason, then al_load_sample() will return NULL, and you shouldn't be trying to do anything with song